diff --git a/src/mod/endpoints/mod_sofia/sofia.c b/src/mod/endpoints/mod_sofia/sofia.c
index 92b84a07ef..0a8d3f812d 100644
--- a/src/mod/endpoints/mod_sofia/sofia.c
+++ b/src/mod/endpoints/mod_sofia/sofia.c
@@ -2509,7 +2509,7 @@ void sofia_handle_sip_i_invite(nua_t *nua, sofia_profile_t *profile, nua_handle_
 	
 
 	if (sess_count >= sess_max || !(profile->pflags & PFLAG_RUNNING)) {
-		nua_respond(nh, 480, "Maximum Calls In Progress", SIPTAG_RETRY_AFTER_STR("300"), TAG_END());
+		nua_respond(nh, 503, "Maximum Calls In Progress", SIPTAG_RETRY_AFTER_STR("300"), TAG_END());
 		return;
 	}
 
@@ -2557,7 +2557,7 @@ void sofia_handle_sip_i_invite(nua_t *nua, sofia_profile_t *profile, nua_handle_
 
 	
 	if (!sofia_endpoint_interface || !(session = switch_core_session_request(sofia_endpoint_interface, NULL))) {
-		nua_respond(nh, 480, "Maximum Calls In Progress", SIPTAG_RETRY_AFTER_STR("300"), TAG_END());
+		nua_respond(nh, 503, "Maximum Calls In Progress", SIPTAG_RETRY_AFTER_STR("300"), TAG_END());
 		return;
 	}
 
@@ -3005,7 +3005,7 @@ void sofia_handle_sip_i_invite(nua_t *nua, sofia_profile_t *profile, nua_handle_
 	nua_handle_bind(nh, NULL);
 	free(tech_pvt->sofia_private);
 	switch_core_session_destroy(&session);
-	nua_respond(nh, 480, "Maximum Calls In Progress", SIPTAG_RETRY_AFTER_STR("300"), TAG_END());
+	nua_respond(nh, 503, "Maximum Calls In Progress", SIPTAG_RETRY_AFTER_STR("300"), TAG_END());
 }
 
 void sofia_handle_sip_i_options(int status,