Index: channels/chan_dahdi.c
===================================================================
--- channels/chan_dahdi.c	(revision 267973)
+++ channels/chan_dahdi.c	(working copy)
@@ -5959,6 +5959,7 @@
 				ast_dsp_digitreset(p->dsp);
 			}
 			if (p->pri->overlapdial & DAHDI_OVERLAPDIAL_INCOMING) {
+				ast_mutex_lock(&p->lock);
 				if (p->pri->pri) {		
 					if (!pri_grab(p, p->pri)) {
 						pri_proceeding(p->pri->pri, p->call, PVT_TO_CHANNEL(p), 0);
@@ -5968,6 +5969,7 @@
 						ast_log(LOG_WARNING, "Unable to grab PRI on span %d\n", p->span);
 					}
 				}
+				ast_mutex_unlock(&p->lock);
 			}
 			dahdi_enable_ec(p);
 			ast_setstate(chan, AST_STATE_RING);