diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 43ee565718..36b3942c63 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -9733,6 +9733,7 @@ static int transmit_register(struct sip_registry *r, int sipmethod, const char *
 	char addr[80];
 	struct sip_pvt *p;
 	int res;
+	char *fromdomain;
 
 	/* exit if we are already in process with this registrar ?*/
 	if (r == NULL || ((auth == NULL) && (r->regstate == REG_STATE_REGSENT || r->regstate == REG_STATE_AUTHSENT))) {
@@ -9851,12 +9852,19 @@ static int transmit_register(struct sip_registry *r, int sipmethod, const char *
 		ast_debug(1, "Scheduled a registration timeout for %s id  #%d \n", r->hostname, r->timeout);
 	}
 
-	if (strchr(r->username, '@')) {
+	if ((fromdomain = strchr(r->username, '@'))) {
+		/* We have a domain in the username for registration */
 		snprintf(from, sizeof(from), "<sip:%s>;tag=%s", r->username, p->tag);
 		if (!ast_strlen_zero(p->theirtag))
 			snprintf(to, sizeof(to), "<sip:%s>;tag=%s", r->username, p->theirtag);
 		else
 			snprintf(to, sizeof(to), "<sip:%s>", r->username);
+
+		/* If the registration username contains '@', then the domain should be used as
+		   the equivalent of "fromdomain" for the registration */
+		if (ast_strlen_zero(p->fromdomain)) {
+			ast_string_field_set(p, fromdomain, ++fromdomain);
+		}
 	} else {
 		snprintf(from, sizeof(from), "<sip:%s@%s>;tag=%s", r->username, p->tohost, p->tag);
 		if (!ast_strlen_zero(p->theirtag))