Switch to audio mode when enabling echo cancellation

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@899 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_zap.c

@@ -907,6 +907,12 @@ static void zt_enable_ec(struct zt_pvt *p)
 		return;
 	}
 	if (p && p->echocancel) {
+		if (p->sig == SIG_PRI) {
+			x = 1;
+			res = ioctl(p->subs[SUB_REAL].zfd, ZT_AUDIOMODE, &x);
+			if (res)
+				ast_log(LOG_WARNING, "Unable to enable echo cancellation on channel %d\n", p->channel);
+		}
 		x = p->echocancel;
 		res = ioctl(p->subs[SUB_REAL].zfd, ZT_ECHOCANCEL, &x);
 		if (res)