No Audio AstGuiClient Manual Dial

[AnkitNpl]

Hi,
When I dial from zoiper, the outbound call connects normally. When dialed manually for outbound campaign from AstGuiClient, the phone rings but no dialtone, no sound, nothing is listened. No issue with inbound calls. I don't see any error in CLI.
Asterisk: 1.8.23.0

Cli Details:
-- Executing [8600062@default:1] MeetMe("Local/8600062@default-000009bd;2", "8600062,F") in new stack
[Feb 11 17:54:39] > Channel Local/8600062@default-000009bd;1 was answered.
[Feb 11 17:54:39] -- Executing [949851111111@default:1] AGI("Local/8600062@default-000009bd;1", "agi://127.0.0.1:4577/call_log") in new stack
[Feb 11 17:54:39] -- AGI Script Executing Application: (EXEC) Options: (Set(_CAMPCUST=OUTBOUND))
[Feb 11 17:54:39] -- <Local/8600062@default-000009bd;1>AGI Script agi://127.0.0.1:4577/call_log completed, returning 0
[Feb 11 17:54:39] -- Executing [949851111118@default:2] Dial("Local/8600062@default-000009bd;1", "SIP/9851111111@gateway4,,tTo") in new stack
[Feb 11 17:54:39] == Using SIP RTP CoS mark 5
[Feb 11 17:54:39] -- Called SIP/9851111111@gateway4
[Feb 11 17:54:40] == Parsing '/etc/asterisk/meetme.conf': [Feb 11 17:54:40] == Found
[Feb 11 17:54:40] == Parsing '/etc/asterisk/meetme-vicidial.conf': [Feb 11 17:54:40] == Found
[Feb 11 17:54:40] -- Created MeetMe conference 1022 for conference '8600062'
[Feb 11 17:54:40] -- <Local/8600062@default-000009bd;2> Playing 'conf-onlyperson.gsm' (language 'en')
[Feb 11 17:54:40] == Manager 'sendcron' logged on from 127.0.0.1
[Feb 11 17:54:40] -- Executing [58600062@default:1] MeetMe("Local/58600062@default-000009be;2", "8600062,Fmq") in new stack
[Feb 11 17:54:40] > Channel Local/58600062@default-000009be;1 was answered.
[Feb 11 17:54:40] -- Executing [8309@default:1] Answer("Local/58600062@default-000009be;1", "") in new stack
[Feb 11 17:54:40] -- Executing [8309@default:2] Monitor("Local/58600062@default-000009be;1", "wav,20150211-175439_9851152978") in new stack
[Feb 11 17:54:40] -- Executing [8309@default:3] Wait("Local/58600062@default-000009be;1", "3600") in new stack
[Feb 11 17:54:40] == Manager 'sendcron' logged off from 127.0.0.1
[Feb 11 17:54:41] == Manager 'sendcron' logged off from 127.0.0.1
[Feb 11 17:54:42] -- SIP/gateway4-00000720 is ringing
[Feb 11 17:54:48] -- SIP/gateway4-00000720 answered Local/8600062@default-000009bd;1

DialPlan:
exten => _94X.,1,AGI(agi://127.0.0.1:4577/call_log)
exten => _94X.,2,Dial(SIP/${EXTEN:2}@gateway4,,tTo)
exten => _94X.,3,Hangup

Kindly request for an expert advise here why NO AUDIO on MANUAL DIAL.

Rgds,

[AnkitNpl]

Further, found following error when agent logs into outbound campaign:

WARNING[16843]: app_meetme.c:4789 admin_exec: Conference number '8600051' not found!
chan_local.c:969 local_call: No such extension/context 8300@default while calling Local channel
NOTICE[16858]: channel.c:5486 __ast_request_and_dial: Unable to call channel Local/8300@default

I suspect the issue came after the Dahdi was upgraded when I received an error "Unable to open DAHDI pseudo device". I followed the instructions from striker24x7.blogspot.in/2013/05/steps-to-reinstall-or-upgrade-dahdi.html.

Any clue?

[AnkitNpl]

Urgent...urgent...seeking for support from you experts...really in trouble..pls help.