if (ast_exists_extension(chan, chan->context, exten, 1, chan->cid.cid_num)) {
                        ast_copy_string(chan->exten, exten, sizeof(chan->exten));
                        if (p->dsp) ast_dsp_digitreset(p->dsp);
                        res = ast_pbx_run(chan);
                        if (res) {
                                ast_log(LOG_WARNING, "PBX exited non-zero\n");
                                res = tone_zone_play_tone(p->subs[index].zfd, ZT_TONE_CONGESTION);
                        }
                        return NULL;
                } else {
                        if (option_verbose > 2)
                                ast_verbose(VERBOSE_PREFIX_2 "Unknown extension '%s' in context '%s' requested\n", exten, chan->context);
                        sleep(2);
                        res = tone_zone_play_tone(p->subs[index].zfd, ZT_TONE_INFO);
                        if (res < 0)
                                ast_log(LOG_WARNING, "Unable to start special tone on %d\n", p->channel);
                        else
                                sleep(1);
                        res = ast_streamfile(chan, "ss-noservice", chan->language);
                        if (res >= 0)
                                ast_waitstream(chan, "");
                        res = tone_zone_play_tone(p->subs[index].zfd, ZT_TONE_CONGESTION);
                        ast_hangup(chan);
                        return NULL;
                }
                break;