Index: channels/chan_sip.c
===================================================================
--- channels/chan_sip.c	(revision 313524)
+++ channels/chan_sip.c	(working copy)
@@ -6234,6 +6249,10 @@
 	struct sip_pvt *p = ast->tech_pvt;
 	int res = 0;
 
+	if (!p) {
+		return res;
+	}
+
 	sip_pvt_lock(p);
 	switch (ast_test_flag(&p->flags[0], SIP_DTMF)) {
 	case SIP_DTMF_INFO: