diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 6c403bc3af..37e82ec003 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -7682,7 +7682,7 @@ static void initreqprep(struct sip_request *req, struct sip_pvt *p, int sipmetho
 
 	if (sipmethod == SIP_NOTIFY && !ast_strlen_zero(p->theirtag)) { 
 		/* If this is a NOTIFY, use the From: tag in the subscribe (RFC 3265) */
-		snprintf(to, sizeof(to), "<sip:%s>;tag=%s", p->uri, p->theirtag);
+		snprintf(to, sizeof(to), "<%s%s>;tag=%s", (strncasecmp(p->uri, "sip:", 4) ? "" : "sip:"), p->uri, p->theirtag);
 	} else if (p->options && p->options->vxml_url) {
 		/* If there is a VXML URL append it to the SIP URL */
 		snprintf(to, sizeof(to), "<%s>;%s", p->uri, p->options->vxml_url);