sig_analog: Skip Caller ID spill if usecallerid=no.

If Caller ID is disabled for an FXS port, then we should not send any
Caller ID spill on the line, as we have no Caller ID information that
we can/should be sending.

Resolves: #1394

channels/sig_analog.c

@@ -390,6 +390,12 @@ static int analog_unalloc_sub(struct analog_pvt *p, enum analog_sub x)
 
 static int analog_send_callerid(struct analog_pvt *p, int cwcid, struct ast_party_caller *caller)
 {
+	/* If Caller ID is disabled for the line, that means we do not send ANY spill whatsoever. */
+	if (!p->use_callerid) {
+		ast_debug(1, "Caller ID is disabled for channel %d, skipping spill\n", p->channel);
+		return 0;
+	}
+
 	ast_debug(1, "Sending callerid.  CID_NAME: '%s' CID_NUM: '%s'\n",
 		caller->id.name.str,
 		caller->id.number.str);

configs/samples/chan_dahdi.conf.sample

@@ -570,6 +570,9 @@ context=public
 ;
 ; Whether or not to use caller ID:
 ;
+; On FXO ports, this enables detecting Caller ID on the incoming phone call.
+; On FXS ports, this enables sending a Caller ID spill to CPE.
+;
 usecallerid=yes
 ;
 ; NOTE: If the CALL_QUALIFIER variable on the channel is set to 1,