diff --git a/pjsip/src/pjsip-ua/sip_inv.c b/pjsip/src/pjsip-ua/sip_inv.c
--- a/pjsip/src/pjsip-ua/sip_inv.c
+++ b/pjsip/src/pjsip-ua/sip_inv.c
@@ -4185,6 +4185,29 @@
 
 	    if (tsx->status_code != 100) {
 
+		if (inv->role == PJSIP_ROLE_UAC) {
+		    pjsip_rx_data *rdata = e->body.tsx_state.src.rdata;
+		    pjsip_allow_hdr *allow = NULL;
+		    pjsip_msg *msg = rdata->msg_info.msg;
+
+		    if (msg) {
+			allow = (pjsip_allow_hdr*) 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) {
+				/* UPDATE is present in Allow */
+				inv->options |= PJSIP_INV_SUPPORT_UPDATE;
+				break;
+			    }
+			}
+		    }
+		}
+
 		if (dlg->remote.info->tag.slen)
 		    inv_set_state(inv, PJSIP_INV_STATE_EARLY, e);