UC500.com

I'm trying to enable T.38 Fax in my network environment using UC520. The setting is something like this:

Fax 1 -- UC520 -- CCM -- VOIP -- PSTN -- Fax 2

Cisco UC520 (using CME) is the originating gateway for fax 1 to send T.38 fax. It is going to the Cisco Unified Call Manager 5.0.4 through SIP trunk.

T.38 has been enabled at the remote terminating gateway, which is using a 3rd party gateway. The receiving fax machine, Fax 2, is currently able to receive fax from other normal fax machine (PSTN & VOIP), but not from Fax 1.

Currently normal voice call can be made from fax 1 (when FXS port is connected to an analog phone) to all the numbers in VOIP and also to all PSTN numbers (local&international). Incoming call can also be received in fax 1.

However, when testing fax call, both Fax 1 and Fax 2 are not able to receive/send fax to each other. In other words, If Fax 1 made a call to Fax 2, there is a ringing tone at the other end but it will just go idle after a while and unable to respond to the fax call.

Therefore, I need some help to check if the following configuration at UC520 is correct, or is there any other way to enable T.38 at the CCM? Currently only SIP trunk to UC520 is configured on the CCM.

Thank you in advance.

===
!
voice service voip
allow-connections sip to sip
no supplementary-service sip moved-temporarily
no supplementary-service sip refer
fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback pass-through g711ulaw
sip
registrar server expires max 3600 min 3600
localhost dns:BWTC.local
!
!
voice class codec 1
codec preference 1 g711ulaw
!
voice-port 0/0/0
ring cadence pattern01
description **FXS Port To Fax Machine**
station-id number 13324400
!
dial-peer voice 2 voip
description **T.38 SIP Trunk To CCM**
destination-pattern [0-9].......T
session protocol sipv2
session target ipv4:80.95.220.110
incoming called-number .T
dtmf-relay h245-signal
codec g711ulaw
fax-relay ecm disable
fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback pass-through g711ulaw
no vad
!
dial-peer voice 10 pots
destination-pattern [0-9].......T
fax rate fax
no digit-strip
port 0/0/0
forward-digits 0
!
!
sip-ua
registrar ipv4:80.95.220.110 expires 3600
!
====