diff --git a/pjsip/src/pjsip-ua/sip_inv.c b/pjsip/src/pjsip-ua/sip_inv.c
new file mode 100644
index 0000000..f9eac98
--- /dev/null
+++ b/pjsip/src/pjsip-ua/sip_inv.c
@@ -0,0 +1,1327 @@
+/* $Id$ */
+/* 
+ * Copyright (C) 2003-2006 Benny Prijono <benny@prijono.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
+ */
+#include <pjsip-ua/sip_inv.h>
+#include <pjsip/sip_module.h>
+#include <pjsip/sip_endpoint.h>
+#include <pjsip/sip_event.h>
+#include <pjsip/sip_transaction.h>
+#include <pjmedia/sdp.h>
+#include <pjmedia/sdp_neg.h>
+#include <pj/string.h>
+#include <pj/pool.h>
+#include <pj/assert.h>
+
+#define THIS_FILE	"sip_invite_session.c"
+
+/*
+ * Static prototypes.
+ */
+static pj_status_t mod_inv_load(pjsip_endpoint *endpt);
+static pj_status_t mod_inv_unload(void);
+static pj_bool_t   mod_inv_on_rx_request(pjsip_rx_data *rdata);
+static pj_bool_t   mod_inv_on_rx_response(pjsip_rx_data *rdata);
+static void	   mod_inv_on_tsx_state(pjsip_transaction*, pjsip_event*);
+
+static void inv_on_state_null( pjsip_inv_session *s, pjsip_event *e);
+static void inv_on_state_calling( pjsip_inv_session *s, pjsip_event *e);
+static void inv_on_state_incoming( pjsip_inv_session *s, pjsip_event *e);
+static void inv_on_state_early( pjsip_inv_session *s, pjsip_event *e);
+static void inv_on_state_connecting( pjsip_inv_session *s, pjsip_event *e);
+static void inv_on_state_confirmed( pjsip_inv_session *s, pjsip_event *e);
+static void inv_on_state_disconnected( pjsip_inv_session *s, pjsip_event *e);
+static void inv_on_state_terminated( pjsip_inv_session *s, pjsip_event *e);
+
+static void (*inv_state_handler[])( pjsip_inv_session *s, pjsip_event *e) = 
+{
+    &inv_on_state_null,
+    &inv_on_state_calling,
+    &inv_on_state_incoming,
+    &inv_on_state_early,
+    &inv_on_state_connecting,
+    &inv_on_state_confirmed,
+    &inv_on_state_disconnected,
+    &inv_on_state_terminated,
+};
+
+static struct mod_inv
+{
+    pjsip_module	 mod;
+    pjsip_endpoint	*endpt;
+    pjsip_inv_callback	 cb;
+    pjsip_module	*app_user;
+} mod_inv = 
+{
+    {
+	NULL, NULL,		    /* prev, next.			*/
+	{ "mod-invite", 10 },	    /* Name.				*/
+	-1,			    /* Id				*/
+	PJSIP_MOD_PRIORITY_APPLICATION-1,	/* Priority		*/
+	NULL,			    /* User data.			*/
+	&mod_inv_load,		    /* load()				*/
+	NULL,			    /* start()				*/
+	NULL,			    /* stop()				*/
+	&mod_inv_unload,	    /* unload()				*/
+	&mod_inv_on_rx_request,	    /* on_rx_request()			*/
+	&mod_inv_on_rx_response,    /* on_rx_response()			*/
+	NULL,			    /* on_tx_request.			*/
+	NULL,			    /* on_tx_response()			*/
+	&mod_inv_on_tsx_state,	    /* on_tsx_state()			*/
+    }
+};
+
+
+
+static pj_status_t mod_inv_load(pjsip_endpoint *endpt)
+{
+    pj_str_t allowed[] = {{"INVITE", 6}, {"ACK",3}, {"BYE",3}, {"CANCEL",6}};
+
+    /* Register supported methods: INVITE, ACK, BYE, CANCEL */
+    pjsip_endpt_add_capability(endpt, &mod_inv.mod, PJSIP_H_ALLOW, NULL,
+			       PJ_ARRAY_SIZE(allowed), allowed);
+
+    return PJ_SUCCESS;
+}
+
+static pj_status_t mod_inv_unload(void)
+{
+    /* Should remove capability here */
+    return PJ_SUCCESS;
+}
+
+static pj_bool_t mod_inv_on_rx_request(pjsip_rx_data *rdata)
+{
+    /* Ignore requests outside dialog */
+    if (pjsip_rdata_get_dlg(rdata) == NULL)
+	return PJ_FALSE;
+
+    /* Ignore all. */
+    return PJ_FALSE;
+}
+
+static pj_status_t send_ack(pjsip_inv_session *inv, pjsip_rx_data *rdata)
+{
+    pjsip_tx_data *tdata;
+    pj_status_t status;
+
+    status = pjsip_dlg_create_request(inv->dlg, &pjsip_ack_method, 
+				      rdata->msg_info.cseq->cseq, &tdata);
+    if (status != PJ_SUCCESS) {
+	/* Better luck next time */
+	pj_assert(!"Unable to create ACK!");
+	return status;
+    }
+
+    status = pjsip_dlg_send_request(inv->dlg, tdata, NULL);
+    if (status != PJ_SUCCESS) {
+	/* Better luck next time */
+	pj_assert(!"Unable to send ACK!");
+	return status;
+    }
+
+    return PJ_SUCCESS;
+}
+
+static pj_bool_t mod_inv_on_rx_response(pjsip_rx_data *rdata)
+{
+    pjsip_dialog *dlg;
+    pjsip_inv_session *inv;
+    pjsip_msg *msg = rdata->msg_info.msg;
+
+    dlg = pjsip_rdata_get_dlg(rdata);
+
+    /* Ignore responses outside dialog */
+    if (dlg == NULL)
+	return PJ_FALSE;
+
+    /* Ignore responses not belonging to invite session */
+    inv = pjsip_dlg_get_inv_session(dlg);
+    if (inv == NULL)
+	return PJ_FALSE;
+
+    /* This MAY be retransmission of 2xx response to INVITE. 
+     * If it is, we need to send ACK.
+     */
+    if (msg->type == PJSIP_RESPONSE_MSG && msg->line.status.code/100==2 &&
+	rdata->msg_info.cseq->method.id == PJSIP_INVITE_METHOD) {
+
+	send_ack(inv, rdata);
+	return PJ_TRUE;
+
+    }
+
+    /* No other processing needs to be done here. */
+    return PJ_FALSE;
+}
+
+static void mod_inv_on_tsx_state(pjsip_transaction *tsx, pjsip_event *e)
+{
+    pjsip_dialog *dlg;
+    pjsip_inv_session *inv;
+
+    dlg = pjsip_tsx_get_dlg(tsx);
+    if (dlg == NULL)
+	return;
+
+    inv = pjsip_dlg_get_inv_session(dlg);
+    if (inv == NULL)
+	return;
+
+    /* Call state handler for the invite session. */
+    (*inv_state_handler[inv->state])(inv, e);
+
+    /* Call on_tsx_state */
+    if (mod_inv.cb.on_tsx_state_changed)
+	(*mod_inv.cb.on_tsx_state_changed)(inv, tsx, e);
+
+    /* Clear invite transaction when tsx is terminated. */
+    if (tsx->state==PJSIP_TSX_STATE_TERMINATED && tsx == inv->invite_tsx)
+	inv->invite_tsx = NULL;
+}
+
+PJ_DEF(pj_status_t) pjsip_inv_usage_init( pjsip_endpoint *endpt,
+					  pjsip_module *app_module,
+					  const pjsip_inv_callback *cb)
+{
+    pj_status_t status;
+
+    /* Check arguments. */
+    PJ_ASSERT_RETURN(endpt && app_module && cb, PJ_EINVAL);
+
+    /* Some callbacks are mandatory */
+    PJ_ASSERT_RETURN(cb->on_state_changed && cb->on_new_session, PJ_EINVAL);
+
+    /* Check if module already registered. */
+    PJ_ASSERT_RETURN(mod_inv.mod.id == -1, PJ_EINVALIDOP);
+
+    /* Copy param. */
+    pj_memcpy(&mod_inv.cb, cb, sizeof(pjsip_inv_callback));
+
+    mod_inv.endpt = endpt;
+    mod_inv.app_user = app_module;
+
+    /* Register the module. */
+    status = pjsip_endpt_register_module(endpt, &mod_inv.mod);
+
+    return status;
+}
+
+PJ_DEF(pjsip_module*) pjsip_inv_usage_instance(void)
+{
+    return &mod_inv.mod;
+}
+
+
+PJ_DEF(pjsip_inv_session*) pjsip_dlg_get_inv_session(pjsip_dialog *dlg)
+{
+    return dlg->mod_data[mod_inv.mod.id];
+}
+
+/*
+ * Create UAC session.
+ */
+PJ_DEF(pj_status_t) pjsip_inv_create_uac( pjsip_dialog *dlg,
+					  const pjmedia_sdp_session *local_sdp,
+					  unsigned options,
+					  pjsip_inv_session **p_inv)
+{
+    pjsip_inv_session *inv;
+    pj_status_t status;
+
+    /* Verify arguments. */
+    PJ_ASSERT_RETURN(dlg && p_inv, PJ_EINVAL);
+
+    /* Normalize options */
+    if (options & PJSIP_INV_REQUIRE_100REL)
+	options |= PJSIP_INV_SUPPORT_100REL;
+
+    if (options & PJSIP_INV_REQUIRE_TIMER)
+	options |= PJSIP_INV_SUPPORT_TIMER;
+
+    /* Create the session */
+    inv = pj_pool_zalloc(dlg->pool, sizeof(pjsip_inv_session));
+    PJ_ASSERT_RETURN(inv != NULL, PJ_ENOMEM);
+
+    inv->pool = dlg->pool;
+    inv->role = PJSIP_ROLE_UAC;
+    inv->state = PJSIP_INV_STATE_NULL;
+    inv->dlg = dlg;
+    inv->options = options;
+
+    /* Create negotiator if local_sdp is specified. */
+    if (local_sdp) {
+	status = pjmedia_sdp_neg_create_w_local_offer(dlg->pool, local_sdp,
+						      &inv->neg);
+	if (status != PJ_SUCCESS)
+	    return status;
+    }
+
+    /* Register invite as dialog usage. */
+    status = pjsip_dlg_add_usage(dlg, &mod_inv.mod, inv);
+    if (status != PJ_SUCCESS)
+	return status;
+
+    /* Increment dialog session */
+    pjsip_dlg_inc_session(dlg);
+
+    /* Done */
+    *p_inv = inv;
+    return PJ_SUCCESS;
+}
+
+/*
+ * Verify incoming INVITE request.
+ */
+PJ_DEF(pj_status_t) pjsip_inv_verify_request(pjsip_rx_data *rdata,
+					     unsigned *options,
+					     const pjmedia_sdp_session *l_sdp,
+					     pjsip_dialog *dlg,
+					     pjsip_endpoint *endpt,
+					     pjsip_tx_data **p_tdata)
+{
+    pjsip_msg *msg;
+    pjsip_allow_hdr *allow;
+    pjsip_supported_hdr *sup_hdr;
+    pjsip_require_hdr *req_hdr;
+    int code = 200;
+    unsigned rem_option = 0;
+    pj_status_t status = PJ_SUCCESS;
+    pjsip_hdr res_hdr_list;
+
+    /* Init return arguments. */
+    if (p_tdata) *p_tdata = NULL;
+
+    /* Verify arguments. */
+    PJ_ASSERT_RETURN(rdata != NULL && options != NULL, PJ_EINVAL);
+
+    /* Normalize options */
+    if (*options & PJSIP_INV_REQUIRE_100REL)
+	*options |= PJSIP_INV_SUPPORT_100REL;
+
+    if (*options & PJSIP_INV_REQUIRE_TIMER)
+	*options |= PJSIP_INV_SUPPORT_TIMER;
+
+    /* Get the message in rdata */
+    msg = rdata->msg_info.msg;
+
+    /* Must be INVITE request. */
+    PJ_ASSERT_RETURN(msg->type == PJSIP_REQUEST_MSG &&
+		     msg->line.req.method.id == PJSIP_INVITE_METHOD,
+		     PJ_EINVAL);
+
+    /* If tdata is specified, then either dlg or endpt must be specified */
+    PJ_ASSERT_RETURN((!p_tdata) || (endpt || dlg), PJ_EINVAL);
+
+    /* Get the endpoint */
+    endpt = endpt ? endpt : dlg->endpt;
+
+    /* Init response header list */
+    pj_list_init(&res_hdr_list);
+
+    /* Check the request body, see if it's something that we support
+     * (i.e. SDP). 
+     */
+    if (msg->body) {
+	pjsip_msg_body *body = msg->body;
+	pj_str_t str_application = {"application", 11};
+	pj_str_t str_sdp = { "sdp", 3 };
+	pjmedia_sdp_session *sdp;
+
+	/* Check content type. */
+	if (pj_stricmp(&body->content_type.type, &str_application) != 0 ||
+	    pj_stricmp(&body->content_type.subtype, &str_sdp) != 0)
+	{
+	    /* Not "application/sdp" */
+	    code = PJSIP_SC_UNSUPPORTED_MEDIA_TYPE;
+	    status = PJSIP_ERRNO_FROM_SIP_STATUS(code);
+
+	    if (p_tdata) {
+		/* Add Accept header to response */
+		pjsip_accept_hdr *acc;
+
+		acc = pjsip_accept_hdr_create(rdata->tp_info.pool);
+		PJ_ASSERT_RETURN(acc, PJ_ENOMEM);
+		acc->values[acc->count++] = pj_str("application/sdp");
+		pj_list_push_back(&res_hdr_list, acc);
+	    }
+
+	    goto on_return;
+	}
+
+	/* Parse and validate SDP */
+	status = pjmedia_sdp_parse(rdata->tp_info.pool, body->data, body->len,
+				   &sdp);
+	if (status == PJ_SUCCESS)
+	    status = pjmedia_sdp_validate(sdp);
+
+	if (status != PJ_SUCCESS) {
+	    /* Unparseable or invalid SDP */
+	    code = PJSIP_SC_BAD_REQUEST;
+
+	    if (p_tdata) {
+		/* Add Warning header. */
+		pjsip_warning_hdr *w;
+
+		w = pjsip_warning_hdr_create_from_status(rdata->tp_info.pool,
+							 pjsip_endpt_name(endpt),
+							 status);
+		PJ_ASSERT_RETURN(w, PJ_ENOMEM);
+
+		pj_list_push_back(&res_hdr_list, w);
+	    }
+
+	    goto on_return;
+	}
+
+	/* Negotiate with local SDP */
+	if (l_sdp) {
+	    pjmedia_sdp_neg *neg;
+
+	    /* Local SDP must be valid! */
+	    PJ_ASSERT_RETURN((status=pjmedia_sdp_validate(l_sdp))==PJ_SUCCESS,
+			     status);
+
+	    /* Create SDP negotiator */
+	    status = pjmedia_sdp_neg_create_w_remote_offer(
+			    rdata->tp_info.pool, l_sdp, sdp, &neg);
+	    PJ_ASSERT_RETURN(status == PJ_SUCCESS, status);
+
+	    /* Negotiate SDP */
+	    status = pjmedia_sdp_neg_negotiate(rdata->tp_info.pool, neg, 0);
+	    if (status != PJ_SUCCESS) {
+
+		/* Incompatible media */
+		code = PJSIP_SC_NOT_ACCEPTABLE_HERE;
+		status = PJSIP_ERRNO_FROM_SIP_STATUS(code);
+
+		if (p_tdata) {
+		    pjsip_accept_hdr *acc;
+		    pjsip_warning_hdr *w;
+
+		    /* Add Warning header. */
+		    w = pjsip_warning_hdr_create_from_status(
+					    rdata->tp_info.pool, 
+					    pjsip_endpt_name(endpt), status);
+		    PJ_ASSERT_RETURN(w, PJ_ENOMEM);
+
+		    pj_list_push_back(&res_hdr_list, w);
+
+		    /* Add Accept header to response */
+		    acc = pjsip_accept_hdr_create(rdata->tp_info.pool);
+		    PJ_ASSERT_RETURN(acc, PJ_ENOMEM);
+		    acc->values[acc->count++] = pj_str("application/sdp");
+		    pj_list_push_back(&res_hdr_list, acc);
+
+		}
+
+		goto on_return;
+	    }
+	}
+    }
+
+    /* Check supported methods, see if peer supports UPDATE.
+     * We just assume that peer supports standard INVITE, ACK, CANCEL, and BYE
+     * implicitly by sending this INVITE.
+     */
+    allow = pjsip_msg_find_hdr(msg, PJSIP_H_ALLOW, NULL);
+    if (allow) {
+	unsigned i;
+	const pj_str_t STR_UPDATE = { "UPDATE", 6 };
+
+	for (i=0; i<allow->count; ++i) {
+	    if (pj_stricmp(&allow->values[i], &STR_UPDATE)==0)
+		break;
+	}
+
+	if (i != allow->count) {
+	    /* UPDATE is present in Allow */
+	    rem_option |= PJSIP_INV_SUPPORT_UPDATE;
+	}
+
+    }
+
+    /* Check Supported header */
+    sup_hdr = pjsip_msg_find_hdr(msg, PJSIP_H_SUPPORTED, NULL);
+    if (sup_hdr) {
+	unsigned i;
+	pj_str_t STR_100REL = { "100rel", 6};
+	pj_str_t STR_TIMER = { "timer", 5 };
+
+	for (i=0; i<sup_hdr->count; ++i) {
+	    if (pj_stricmp(&sup_hdr->values[i], &STR_100REL)==0)
+		rem_option |= PJSIP_INV_SUPPORT_100REL;
+	    else if (pj_stricmp(&sup_hdr->values[i], &STR_TIMER)==0)
+		rem_option |= PJSIP_INV_SUPPORT_TIMER;
+	}
+    }
+
+    /* Check Require header */
+    req_hdr = pjsip_msg_find_hdr(msg, PJSIP_H_REQUIRE, NULL);
+    if (req_hdr) {
+	unsigned i;
+	pj_str_t STR_100REL = { "100rel", 6};
+	pj_str_t STR_TIMER = { "timer", 5 };
+	unsigned unsupp_cnt = 0;
+	pj_str_t unsupp_tags[PJSIP_GENERIC_ARRAY_MAX_COUNT];
+	
+	for (i=0; i<req_hdr->count; ++i) {
+	    if ((*options & PJSIP_INV_SUPPORT_100REL) && 
+		pj_stricmp(&req_hdr->values[i], &STR_100REL)==0)
+	    {
+		rem_option |= PJSIP_INV_REQUIRE_100REL;
+
+	    } else if ((*options && PJSIP_INV_SUPPORT_TIMER) &&
+		       pj_stricmp(&req_hdr->values[i], &STR_TIMER)==0)
+	    {
+		rem_option |= PJSIP_INV_REQUIRE_TIMER;
+
+	    } else {
+		/* Unknown/unsupported extension tag!  */
+		unsupp_tags[unsupp_cnt++] = req_hdr->values[i];
+	    }
+	}
+
+	/* Check if there are required tags that we don't support */
+	if (unsupp_cnt) {
+
+	    code = PJSIP_SC_BAD_EXTENSION;
+	    status = PJSIP_ERRNO_FROM_SIP_STATUS(code);
+
+	    if (p_tdata) {
+		pjsip_unsupported_hdr *unsupp_hdr;
+		const pjsip_hdr *h;
+
+		/* Add Unsupported header. */
+		unsupp_hdr = pjsip_unsupported_hdr_create(rdata->tp_info.pool);
+		PJ_ASSERT_RETURN(unsupp_hdr != NULL, PJ_ENOMEM);
+
+		unsupp_hdr->count = unsupp_cnt;
+		for (i=0; i<unsupp_cnt; ++i)
+		    unsupp_hdr->values[i] = unsupp_tags[i];
+
+		pj_list_push_back(&res_hdr_list, unsupp_hdr);
+
+		/* Add Supported header. */
+		h = pjsip_endpt_get_capability(endpt, PJSIP_H_SUPPORTED, 
+					       NULL);
+		pj_assert(h);
+		if (h) {
+		    sup_hdr = pjsip_hdr_clone(rdata->tp_info.pool, h);
+		    pj_list_push_back(&res_hdr_list, sup_hdr);
+		}
+	    }
+
+	    goto on_return;
+	}
+    }
+
+    /* Check if there are local requirements that are not supported
+     * by peer.
+     */
+    if ( ((*options & PJSIP_INV_REQUIRE_100REL)!=0 && 
+	  (rem_option & PJSIP_INV_SUPPORT_100REL)==0) ||
+	 ((*options & PJSIP_INV_REQUIRE_TIMER)!=0 &&
+	  (rem_option & PJSIP_INV_SUPPORT_TIMER)==0))
+    {
+	code = PJSIP_SC_EXTENSION_REQUIRED;
+	status = PJSIP_ERRNO_FROM_SIP_STATUS(code);
+
+	if (p_tdata) {
+	    const pjsip_hdr *h;
+
+	    /* Add Require header. */
+	    req_hdr = pjsip_require_hdr_create(rdata->tp_info.pool);
+	    PJ_ASSERT_RETURN(req_hdr != NULL, PJ_ENOMEM);
+
+	    if (*options & PJSIP_INV_REQUIRE_100REL)
+		req_hdr->values[req_hdr->count++] = pj_str("100rel");
+
+	    if (*options & PJSIP_INV_REQUIRE_TIMER)
+		req_hdr->values[req_hdr->count++] = pj_str("timer");
+
+	    pj_list_push_back(&res_hdr_list, req_hdr);
+
+	    /* Add Supported header. */
+	    h = pjsip_endpt_get_capability(endpt, PJSIP_H_SUPPORTED, 
+					   NULL);
+	    pj_assert(h);
+	    if (h) {
+		sup_hdr = pjsip_hdr_clone(rdata->tp_info.pool, h);
+		pj_list_push_back(&res_hdr_list, sup_hdr);
+	    }
+
+	}
+
+	goto on_return;
+    }
+
+on_return:
+
+    /* Create response if necessary */
+    if (code != 200 && p_tdata) {
+	pjsip_tx_data *tdata;
+	const pjsip_hdr *h;
+
+	if (dlg) {
+	    status = pjsip_dlg_create_response(dlg, rdata, code, NULL, 
+					       &tdata);
+	} else {
+	    status = pjsip_endpt_create_response(endpt, rdata, code, NULL, 
+						 &tdata);
+	}
+
+	if (status != PJ_SUCCESS)
+	    return status;
+
+	/* Add response headers. */
+	h = res_hdr_list.next;
+	while (h != &res_hdr_list) {
+	    pjsip_hdr *cloned;
+
+	    cloned = pjsip_hdr_clone(tdata->pool, h);
+	    PJ_ASSERT_RETURN(cloned, PJ_ENOMEM);
+
+	    pjsip_msg_add_hdr(tdata->msg, cloned);
+
+	    h = h->next;
+	}
+
+	*p_tdata = tdata;
+    }
+
+    return status;
+}
+
+/*
+ * Create UAS session.
+ */
+PJ_DEF(pj_status_t) pjsip_inv_create_uas( pjsip_dialog *dlg,
+					  pjsip_rx_data *rdata,
+					  const pjmedia_sdp_session *local_sdp,
+					  unsigned options,
+					  pjsip_inv_session **p_inv)
+{
+    pjsip_inv_session *inv;
+    pjsip_msg *msg;
+    pjmedia_sdp_session *rem_sdp = NULL;
+    pj_status_t status;
+
+    /* Verify arguments. */
+    PJ_ASSERT_RETURN(dlg && rdata && p_inv, PJ_EINVAL);
+
+    /* Dialog MUST have been initialised. */
+    PJ_ASSERT_RETURN(pjsip_rdata_get_tsx(rdata) != NULL, PJ_EINVALIDOP);
+
+    msg = rdata->msg_info.msg;
+
+    /* rdata MUST contain INVITE request */
+    PJ_ASSERT_RETURN(msg->type == PJSIP_REQUEST_MSG &&
+		     msg->line.req.method.id == PJSIP_INVITE_METHOD,
+		     PJ_EINVALIDOP);
+
+    /* Normalize options */
+    if (options & PJSIP_INV_REQUIRE_100REL)
+	options |= PJSIP_INV_SUPPORT_100REL;
+
+    if (options & PJSIP_INV_REQUIRE_TIMER)
+	options |= PJSIP_INV_SUPPORT_TIMER;
+
+    /* Create the session */
+    inv = pj_pool_zalloc(dlg->pool, sizeof(pjsip_inv_session));
+    PJ_ASSERT_RETURN(inv != NULL, PJ_ENOMEM);
+
+    inv->pool = dlg->pool;
+    inv->role = PJSIP_ROLE_UAS;
+    inv->state = PJSIP_INV_STATE_NULL;
+    inv->dlg = dlg;
+    inv->options = options;
+
+    /* Parse SDP in message body, if present. */
+    if (msg->body) {
+	pjsip_msg_body *body = msg->body;
+
+	/* Parse and validate SDP */
+	status = pjmedia_sdp_parse(inv->pool, body->data, body->len,
+				   &rem_sdp);
+	if (status == PJ_SUCCESS)
+	    status = pjmedia_sdp_validate(rem_sdp);
+
+	if (status != PJ_SUCCESS)
+	    return status;
+    }
+
+    /* Create negotiator. */
+    if (rem_sdp) {
+	status = pjmedia_sdp_neg_create_w_remote_offer(inv->pool, local_sdp,
+						       rem_sdp, &inv->neg);
+						
+    } else if (local_sdp) {
+	status = pjmedia_sdp_neg_create_w_local_offer(inv->pool, local_sdp,
+						      &inv->neg);
+    } else {
+	pj_assert(!"UAS dialog without remote and local offer is not supported!");
+	PJ_TODO(IMPLEMENT_DELAYED_UAS_OFFER);
+	status = PJ_ENOTSUP;
+    }
+
+    if (status != PJ_SUCCESS)
+	return status;
+
+    /* Register invite as dialog usage. */
+    status = pjsip_dlg_add_usage(dlg, &mod_inv.mod, inv);
+    if (status != PJ_SUCCESS)
+	return status;
+
+    /* Increment session in the dialog. */
+    pjsip_dlg_inc_session(dlg);
+
+    /* Save the invite transaction. */
+    inv->invite_tsx = pjsip_rdata_get_tsx(rdata);
+    inv->invite_tsx->mod_data[mod_inv.mod.id] = inv;
+
+    /* Done */
+    *p_inv = inv;
+    return PJ_SUCCESS;
+}
+
+static void *clone_sdp(pj_pool_t *pool, const void *data, unsigned len)
+{
+    PJ_UNUSED_ARG(len);
+    return pjmedia_sdp_session_clone(pool, data);
+}
+
+static int print_sdp(pjsip_msg_body *body, char *buf, pj_size_t len)
+{
+    return pjmedia_sdp_print(body->data, buf, len);
+}
+
+static pjsip_msg_body *create_sdp_body(pj_pool_t *pool,
+				       const pjmedia_sdp_session *c_sdp)
+{
+    pjsip_msg_body *body;
+
+
+    body = pj_pool_zalloc(pool, sizeof(pjsip_msg_body));
+    PJ_ASSERT_RETURN(body != NULL, NULL);
+
+    body->content_type.type = pj_str("application");
+    body->content_type.subtype = pj_str("sdp");
+    body->data = pjmedia_sdp_session_clone(pool, c_sdp);
+    body->len = 0;
+    body->clone_data = &clone_sdp;
+    body->print_body = &print_sdp;
+
+    return body;
+}
+
+/*
+ * Create initial INVITE request.
+ */
+PJ_DEF(pj_status_t) pjsip_inv_invite( pjsip_inv_session *inv,
+				      pjsip_tx_data **p_tdata )
+{
+    pjsip_tx_data *tdata;
+    const pjsip_hdr *hdr;
+    pj_status_t status;
+
+    /* Verify arguments. */
+    PJ_ASSERT_RETURN(inv && p_tdata, PJ_EINVAL);
+
+    /* State MUST be NULL. */
+    PJ_ASSERT_RETURN(inv->state == PJSIP_INV_STATE_NULL, PJ_EINVAL);
+
+    /* Create the INVITE request. */
+    status = pjsip_dlg_create_request(inv->dlg, &pjsip_invite_method, -1,
+				      &tdata);
+    if (status != PJ_SUCCESS)
+	return status;
+
+    /* Add SDP, if any. */
+    if (inv->neg && 
+	pjmedia_sdp_neg_get_state(inv->neg)==PJMEDIA_SDP_NEG_STATE_LOCAL_OFFER)
+    {
+	const pjmedia_sdp_session *offer;
+
+	status = pjmedia_sdp_neg_get_neg_local(inv->neg, &offer);
+	if (status != PJ_SUCCESS)
+	    return status;
+
+	tdata->msg->body = create_sdp_body(tdata->pool, offer);
+    }
+
+    /* Add Allow header. */
+    hdr = pjsip_endpt_get_capability(inv->dlg->endpt, PJSIP_H_ALLOW, NULL);
+    if (hdr) {
+	pjsip_msg_add_hdr(tdata->msg,
+			  pjsip_hdr_shallow_clone(tdata->pool, hdr));
+    }
+
+    /* Add Supported header */
+    hdr = pjsip_endpt_get_capability(inv->dlg->endpt, PJSIP_H_SUPPORTED, NULL);
+    if (hdr) {
+	pjsip_msg_add_hdr(tdata->msg,
+			  pjsip_hdr_shallow_clone(tdata->pool, hdr));
+    }
+
+    /* Add Require header. */
+    PJ_TODO(INVITE_ADD_REQUIRE_HEADER);
+
+    /* Done. */
+    *p_tdata = tdata;
+
+    return PJ_SUCCESS;
+}
+
+
+/*
+ * Answer initial INVITE.
+ */ 
+PJ_DEF(pj_status_t) pjsip_inv_answer(	pjsip_inv_session *inv,
+					int st_code,
+					const pj_str_t *st_text,
+					const pjmedia_sdp_session *local_sdp,
+					pjsip_tx_data **p_tdata )
+{
+    pjsip_tx_data *last_res;
+    pj_status_t status;
+
+    /* Verify arguments. */
+    PJ_ASSERT_RETURN(inv && p_tdata, PJ_EINVAL);
+
+    /* Must have INVITE transaction. */
+    PJ_ASSERT_RETURN(inv->invite_tsx, PJ_EBUG);
+
+    /* INVITE transaction MUST have transmitted a response (e.g. 100) */
+    PJ_ASSERT_RETURN(inv->invite_tsx->last_tx, PJ_EINVALIDOP);
+
+    /* If local_sdp is specified, then we MUST NOT have answered the
+     * offer before. 
+     */
+    PJ_ASSERT_RETURN(!local_sdp ||
+		     (pjmedia_sdp_neg_get_state(inv->neg)==PJMEDIA_SDP_NEG_STATE_REMOTE_OFFER),
+		     PJ_EINVALIDOP);
+    if (local_sdp) {
+	status = pjmedia_sdp_neg_set_local_answer(inv->pool, inv->neg,
+						  local_sdp);
+	if (status != PJ_SUCCESS)
+	    return status;
+    }
+
+    last_res = inv->invite_tsx->last_tx;
+
+    /* Modify last response. */
+    status = pjsip_dlg_modify_response(inv->dlg, last_res, st_code, st_text);
+    if (status != PJ_SUCCESS)
+	return status;
+
+    /* Include SDP for 18x and 2xx response. */
+    if (st_code/10 == 18 || st_code/10 == 20) {
+	pjmedia_sdp_session *local;
+
+	status = pjmedia_sdp_neg_get_neg_local(inv->neg, &local);
+	if (status == PJ_SUCCESS)
+	    last_res->msg->body = create_sdp_body(last_res->pool, local);
+					      ;
+    }
+
+    /* Do we need to increment tdata's reference counter? */
+    PJ_TODO(INV_ANSWER_MAY_HAVE_TO_INCREMENT_REF_COUNTER);
+
+    *p_tdata = last_res;
+
+    return PJ_SUCCESS;
+}
+
+
+/*
+ * End session.
+ */
+PJ_DEF(pj_status_t) pjsip_inv_end_session(  pjsip_inv_session *inv,
+					    int st_code,
+					    const pj_str_t *st_text,
+					    pjsip_tx_data **p_tdata )
+{
+    pjsip_tx_data *tdata;
+    pj_status_t status;
+
+    /* Verify arguments. */
+    PJ_ASSERT_RETURN(inv && p_tdata, PJ_EINVAL);
+
+    /* Create appropriate message. */
+    switch (inv->state) {
+    case PJSIP_INV_STATE_CALLING:
+    case PJSIP_INV_STATE_EARLY:
+    case PJSIP_INV_STATE_INCOMING:
+
+	if (inv->role == PJSIP_ROLE_UAC) {
+
+	    /* For UAC when session has not been confirmed, create CANCEL. */
+
+	    /* MUST have the original UAC INVITE transaction. */
+	    PJ_ASSERT_RETURN(inv->invite_tsx != NULL, PJ_EBUG);
+
+	    /* But CANCEL should only be called when we have received a
+	     * provisional response. If we haven't received any responses,
+	     * just destroy the transaction.
+	     */
+	    if (inv->invite_tsx->status_code < 100) {
+
+		pjsip_tsx_terminate(inv->invite_tsx, 487);
+
+		return PJSIP_ETSXDESTROYED;
+	    }
+
+	    /* The CSeq here assumes that the dialog is started with an
+	     * INVITE session. This may not be correct; dialog can be 
+	     * started as SUBSCRIBE session.
+	     * So fix this!
+	     */
+	    status = pjsip_endpt_create_cancel(inv->dlg->endpt, 
+					       inv->invite_tsx->last_tx,
+					       &tdata);
+
+	} else {
+
+	    /* For UAS, send a final response. */
+	    tdata = inv->invite_tsx->last_tx;
+	    PJ_ASSERT_RETURN(tdata != NULL, PJ_EINVALIDOP);
+
+	    status = pjsip_dlg_modify_response(inv->dlg, tdata, st_code,
+					       st_text);
+	}
+	break;
+
+    case PJSIP_INV_STATE_CONNECTING:
+    case PJSIP_INV_STATE_CONFIRMED:
+	/* For established dialog, send BYE */
+	status = pjsip_dlg_create_request(inv->dlg, &pjsip_bye_method, -1, 
+					  &tdata);
+	break;
+
+    case PJSIP_INV_STATE_DISCONNECTED:
+    case PJSIP_INV_STATE_TERMINATED:
+	/* No need to do anything. */
+	PJ_TODO(RETURN_A_PROPER_STATUS_CODE_HERE);
+	return PJ_EINVALIDOP;
+
+    default:
+	pj_assert("!Invalid operation!");
+	return PJ_EINVALIDOP;
+    }
+
+    if (status != PJ_SUCCESS)
+	return status;
+
+
+    /* Done */
+
+    *p_tdata = tdata;
+
+    return PJ_SUCCESS;
+}
+
+
+/*
+ * Create re-INVITE.
+ */
+PJ_DEF(pj_status_t) pjsip_inv_reinvite( pjsip_inv_session *inv,
+					const pj_str_t *new_contact,
+					const pjmedia_sdp_session *new_offer,
+					pjsip_tx_data **p_tdata )
+{
+    PJ_UNUSED_ARG(inv);
+    PJ_UNUSED_ARG(new_contact);
+    PJ_UNUSED_ARG(new_offer);
+    PJ_UNUSED_ARG(p_tdata);
+
+    PJ_TODO(CREATE_REINVITE_REQUEST);
+    return PJ_ENOTSUP;
+}
+
+/*
+ * Create UPDATE.
+ */
+PJ_DEF(pj_status_t) pjsip_inv_update (	pjsip_inv_session *inv,
+					const pj_str_t *new_contact,
+					const pjmedia_sdp_session *new_offer,
+					pjsip_tx_data **p_tdata )
+{
+    PJ_UNUSED_ARG(inv);
+    PJ_UNUSED_ARG(new_contact);
+    PJ_UNUSED_ARG(new_offer);
+    PJ_UNUSED_ARG(p_tdata);
+
+    PJ_TODO(CREATE_UPDATE_REQUEST);
+    return PJ_ENOTSUP;
+}
+
+/*
+ * Send a request or response message.
+ */
+PJ_DEF(pj_status_t) pjsip_inv_send_msg( pjsip_inv_session *inv,
+					pjsip_tx_data *tdata,
+					void *token )
+{
+    pj_status_t status;
+
+    /* Verify arguments. */
+    PJ_ASSERT_RETURN(inv && tdata, PJ_EINVAL);
+
+    if (tdata->msg->type == PJSIP_REQUEST_MSG) {
+	pjsip_transaction *tsx;
+
+	status = pjsip_dlg_send_request(inv->dlg, tdata, &tsx);
+	if (status != PJ_SUCCESS)
+	    return status;
+
+	tsx->mod_data[mod_inv.mod.id] = inv;
+	tsx->mod_data[mod_inv.app_user->id] = token;
+
+    } else {
+	pjsip_cseq_hdr *cseq;
+
+	/* Can only do this to send response to original INVITE
+	 * request.
+	 */
+	PJ_ASSERT_RETURN((cseq=pjsip_msg_find_hdr(tdata->msg, PJSIP_H_CSEQ, NULL)) != NULL &&
+			 (cseq->cseq == inv->invite_tsx->cseq),
+			 PJ_EINVALIDOP);
+
+	status = pjsip_dlg_send_response(inv->dlg, inv->invite_tsx, tdata);
+	if (status != PJ_SUCCESS)
+	    return status;
+    }
+
+    /* Done (?) */
+    return PJ_SUCCESS;
+}
+
+
+void inv_set_state(pjsip_inv_session *inv, pjsip_inv_state state,
+		   pjsip_event *e)
+{
+    inv->state = state;
+    if (mod_inv.cb.on_state_changed)
+	(*mod_inv.cb.on_state_changed)(inv, e);
+
+    if (inv->state == PJSIP_INV_STATE_DISCONNECTED)
+	pjsip_dlg_dec_session(inv->dlg);
+}
+
+static void inv_on_state_null( pjsip_inv_session *s, pjsip_event *e)
+{
+    pjsip_transaction *tsx = e->body.tsx_state.tsx;
+    pjsip_dialog *dlg = pjsip_tsx_get_dlg(tsx);
+
+    PJ_ASSERT_ON_FAIL(tsx && dlg, return);
+
+    if (tsx->method.id == PJSIP_INVITE_METHOD) {
+
+	if (dlg->role == PJSIP_ROLE_UAC) {
+
+	    /* Keep the initial INVITE transaction. */
+	    if (s->invite_tsx == NULL)
+		s->invite_tsx = tsx;
+
+	    switch (tsx->state) {
+	    case PJSIP_TSX_STATE_CALLING:
+		inv_set_state(s, PJSIP_INV_STATE_CALLING, e);
+		break;
+	    default:
+		pj_assert(!"Unexpected state");
+		break;
+	    }
+
+	} else {
+	    switch (tsx->state) {
+	    case PJSIP_TSX_STATE_TRYING:
+		inv_set_state(s, PJSIP_INV_STATE_INCOMING, e);
+		break;
+	    default:
+		pj_assert(!"Unexpected state");
+	    }
+	}
+
+    } else {
+	pj_assert(!"Unexpected transaction type");
+    }
+}
+
+static void inv_on_state_calling( pjsip_inv_session *s, pjsip_event *e)
+{
+    pjsip_transaction *tsx = e->body.tsx_state.tsx;
+    pjsip_dialog *dlg = pjsip_tsx_get_dlg(tsx);
+
+    PJ_ASSERT_ON_FAIL(tsx && dlg, return);
+    
+    if (tsx->method.id == PJSIP_INVITE_METHOD) {
+
+	switch (tsx->state) {
+
+	case PJSIP_TSX_STATE_PROCEEDING:
+	    if (dlg->remote.info->tag.slen) {
+		inv_set_state(s, PJSIP_INV_STATE_EARLY, e);
+	    } else {
+		/* Ignore 100 (Trying) response, as it doesn't change
+		 * session state. It only ceases retransmissions.
+		 */
+	    }
+	    break;
+
+	case PJSIP_TSX_STATE_COMPLETED:
+	    if (tsx->status_code/100 == 2) {
+		
+		/* This should not happen.
+		 * When transaction receives 2xx, it should be terminated
+		 */
+		pj_assert(0);
+		inv_set_state(s, PJSIP_INV_STATE_CONNECTING, e);
+
+	    } else {
+		inv_set_state(s, PJSIP_INV_STATE_DISCONNECTED, e);
+	    }
+	    break;
+
+	case PJSIP_TSX_STATE_TERMINATED:
+	    /* INVITE transaction can be terminated either because UAC
+	     * transaction received 2xx response or because of transport
+	     * error.
+	     */
+	    if (tsx->status_code/100 == 2) {
+		/* This must be receipt of 2xx response */
+
+		/* Set state to CONNECTING */
+		inv_set_state(s, PJSIP_INV_STATE_CONNECTING, e);
+
+		/* Send ACK */
+		pj_assert(e->body.tsx_state.type == PJSIP_EVENT_RX_MSG);
+
+		send_ack(s, e->body.tsx_state.src.rdata);
+
+	    } else  {
+		inv_set_state(s, PJSIP_INV_STATE_DISCONNECTED, e);
+		inv_set_state(s, PJSIP_INV_STATE_TERMINATED, e);
+	    }
+	    break;
+
+	default:
+	    pj_assert(!"Unexpected state");
+	}
+
+    } else {
+	pj_assert(!"Unexpected transaction type");
+    }
+}
+
+static void inv_on_state_incoming( pjsip_inv_session *s, pjsip_event *e)
+{
+    pjsip_transaction *tsx = e->body.tsx_state.tsx;
+    pjsip_dialog *dlg = pjsip_tsx_get_dlg(tsx);
+
+    PJ_ASSERT_ON_FAIL(tsx && dlg, return);
+
+    if (tsx->method.id == PJSIP_INVITE_METHOD) {
+	switch (tsx->state) {
+	case PJSIP_TSX_STATE_PROCEEDING:
+	    if (tsx->status_code > 100)
+		inv_set_state(s, PJSIP_INV_STATE_EARLY, e);
+	    break;
+	case PJSIP_TSX_STATE_COMPLETED:
+	    if (tsx->status_code/100 == 2)
+		inv_set_state(s, PJSIP_INV_STATE_CONNECTING, e);
+	    else
+		inv_set_state(s, PJSIP_INV_STATE_DISCONNECTED, e);
+	    break;
+	case PJSIP_TSX_STATE_TERMINATED:
+	    /* This happens on transport error */
+	    inv_set_state(s, PJSIP_INV_STATE_DISCONNECTED, e);
+	    inv_set_state(s, PJSIP_INV_STATE_TERMINATED, e);
+	    break;
+	default:
+	    pj_assert(!"Unexpected state");
+	}
+    } else {
+	pj_assert(!"Unexpected transaction type");
+    }
+}
+
+static void inv_on_state_early( pjsip_inv_session *s, pjsip_event *e)
+{
+    pjsip_transaction *tsx = e->body.tsx_state.tsx;
+    pjsip_dialog *dlg = pjsip_tsx_get_dlg(tsx);
+
+    PJ_ASSERT_ON_FAIL(tsx && dlg, return);
+
+    if (tsx->method.id == PJSIP_INVITE_METHOD) {
+
+	switch (tsx->state) {
+
+	case PJSIP_TSX_STATE_PROCEEDING:
+	    /* Send/received another provisional response. */
+	    inv_set_state(s, PJSIP_INV_STATE_EARLY, e);
+	    break;
+
+	case PJSIP_TSX_STATE_COMPLETED:
+	    if (tsx->status_code/100 == 2)
+		inv_set_state(s, PJSIP_INV_STATE_CONNECTING, e);
+	    else
+		inv_set_state(s, PJSIP_INV_STATE_DISCONNECTED, e);
+	    break;
+
+	case PJSIP_TSX_STATE_TERMINATED:
+	    /* INVITE transaction can be terminated either because UAC
+	     * transaction received 2xx response or because of transport
+	     * error.
+	     */
+	    if (tsx->status_code/100 == 2) {
+
+		/* This must be receipt of 2xx response */
+
+		/* Set state to CONNECTING */
+		inv_set_state(s, PJSIP_INV_STATE_CONNECTING, e);
+
+		/* if UAC, send ACK and move state to confirmed. */
+		if (tsx->role == PJSIP_ROLE_UAC) {
+		    pj_assert(e->body.tsx_state.type == PJSIP_EVENT_RX_MSG);
+
+		    send_ack(s, e->body.tsx_state.src.rdata);
+
+		    inv_set_state(s, PJSIP_INV_STATE_CONFIRMED, e);
+		}
+
+	    } else  {
+		inv_set_state(s, PJSIP_INV_STATE_DISCONNECTED, e);
+		inv_set_state(s, PJSIP_INV_STATE_TERMINATED, e);
+	    }
+	    break;
+
+	default:
+	    pj_assert(!"Unexpected state");
+	}
+
+    } else if (tsx->method.id == PJSIP_CANCEL_METHOD) {
+
+	/* Handle incoming CANCEL request. */
+	if (tsx->role == PJSIP_ROLE_UAS && s->role == PJSIP_ROLE_UAS &&
+	    e->body.tsx_state.type == PJSIP_EVENT_RX_MSG) 
+	{
+
+	    pj_status_t status;
+	    pjsip_tx_data *tdata;
+
+	    /* Respond CANCEL with 200 (OK) */
+	    status = pjsip_dlg_create_response(dlg, e->body.tsx_state.src.rdata,
+					       200, NULL, &tdata);
+	    if (status == PJ_SUCCESS) {
+		pjsip_dlg_send_response(dlg, tsx, tdata);
+	    }
+    
+	    /* Respond the original UAS transaction with 487 (Request 
+	     * Terminated) response.
+	     */
+	    pj_assert(s->invite_tsx && s->invite_tsx->last_tx);
+	    tdata = s->invite_tsx->last_tx;
+
+	    status = pjsip_dlg_modify_response(dlg, tdata, 487, NULL);
+	    if (status == PJ_SUCCESS) {
+		pjsip_dlg_send_response(dlg, s->invite_tsx, tdata);
+	    }
+	}
+
+    } else {
+	pj_assert(!"Unexpected transaction type");
+    }
+}
+
+static void inv_on_state_connecting( pjsip_inv_session *s, pjsip_event *e)
+{
+    pjsip_transaction *tsx = e->body.tsx_state.tsx;
+    pjsip_dialog *dlg = pjsip_tsx_get_dlg(tsx);
+
+    PJ_ASSERT_ON_FAIL(tsx && dlg, return);
+
+    if (tsx->method.id == PJSIP_INVITE_METHOD) {
+
+	switch (tsx->state) {
+
+	case PJSIP_TSX_STATE_CONFIRMED:
+	    break;
+
+	case PJSIP_TSX_STATE_TERMINATED:
+	    /* INVITE transaction can be terminated either because UAC
+	     * transaction received 2xx response or because of transport
+	     * error.
+	     */
+	    if (tsx->status_code/100 != 2) {
+		inv_set_state(s, PJSIP_INV_STATE_DISCONNECTED, e);
+		inv_set_state(s, PJSIP_INV_STATE_TERMINATED, e);
+	    }
+	    break;
+
+	case PJSIP_TSX_STATE_DESTROYED:
+	    /* Do nothing. */
+	    break;
+
+	default:
+	    pj_assert(!"Unexpected state");
+	}
+
+    } else {
+	pj_assert(!"Unexpected transaction type");
+    }
+}
+
+static void inv_on_state_confirmed( pjsip_inv_session *s, pjsip_event *e)
+{
+    pjsip_transaction *tsx = e->body.tsx_state.tsx;
+    pjsip_dialog *dlg = pjsip_tsx_get_dlg(tsx);
+
+    PJ_ASSERT_ON_FAIL(tsx && dlg, return);
+
+    if (tsx->method.id == PJSIP_BYE_METHOD) {
+	inv_set_state(s, PJSIP_INV_STATE_DISCONNECTED, e);
+
+    } else if (tsx->method.id == PJSIP_INVITE_METHOD) {
+	
+	switch (tsx->state) {
+	case PJSIP_TSX_STATE_TERMINATED:
+	case PJSIP_TSX_STATE_DESTROYED:
+	    break;
+	default:
+	    pj_assert(!"Unexpected state");
+	    break;
+	}
+
+
+    } else {
+	pj_assert(!"Unexpected transaction type");
+    }
+}
+
+static void inv_on_state_disconnected( pjsip_inv_session *s, pjsip_event *e)
+{
+    PJ_UNUSED_ARG(s);
+    PJ_UNUSED_ARG(e);
+}
+
+static void inv_on_state_terminated( pjsip_inv_session *s, pjsip_event *e)
+{
+    PJ_UNUSED_ARG(s);
+    PJ_UNUSED_ARG(e);
+}
+