try to auto guess presence_id where possible

src/mod/applications/mod_dptools/mod_dptools.c

@@ -3313,6 +3313,9 @@ static switch_call_cause_t user_outgoing_channel(switch_core_session_t *session,
 	if (var_event) {
 		switch_event_add_header_string(var_event, SWITCH_STACK_BOTTOM, "dialed_user", user);
 		switch_event_add_header_string(var_event, SWITCH_STACK_BOTTOM, "dialed_domain", domain);
+		if (!strstr(dest, "presence_id=")) {
+			switch_event_add_header(var_event, SWITCH_STACK_BOTTOM, "presence_id", "%s@%s", user, domain);
+		}
 	}
 
 	if (!dest) {

src/mod/endpoints/mod_sofia/sofia_glue.c

@@ -2291,6 +2291,25 @@ switch_status_t sofia_glue_do_invite(switch_core_session_t *session)
 		switch_channel_set_variable(channel, "sip_to_host", sofia_glue_get_host(to_str, switch_core_session_get_pool(session)));
 		switch_channel_set_variable(channel, "sip_from_host", sofia_glue_get_host(from_str, switch_core_session_get_pool(session)));
 
+		if (!switch_channel_get_variable(channel, "presence_id")) {
+			char *from = switch_core_session_strdup(session, from_str);
+			
+			if (!strncasecmp(from, "sip:", 4)) {
+				from += 4;
+			}
+
+			if (!strncasecmp(from, "sips:", 4)) {
+				from += 5;
+			}
+
+			if ((p = strchr(from, ':')) || (p = strchr(from, ';'))) {
+				*p++ = '\0';
+			}
+			
+			switch_channel_set_variable(channel, "presence_id", from);
+			
+		}
+		
 		if (!(tech_pvt->nh = nua_handle(tech_pvt->profile->nua, NULL,
 										NUTAG_URL(url_str),
 										TAG_IF(call_id, SIPTAG_CALL_ID_STR(call_id)),