How to configure modem connection with GW (H323) and ATA 187

[Michael Endler]

Hello Community,

i stock in configuration and need assistance.
My callflow: Telco – PRI – GW – H323– CUCM – SIP – ATA187 – Modem
Voicegateway (Version 15.3(2)T) + CUCM (Version= 8.6) + ATA187 (Version= 9.2.3.1)

The modem connection is still not working.

What is still to configure on the voicegateway? modem passthrough?

Regards Michael

ATA 187 Configuration:
Fax Mode= T.38 Fax Relay
Fax Error Correction Mode Override= Off
Maximum Fax Rate= 14000bps
Impedance= 900Ohms complex

Gateway Configuration:
voice service voip
 ip address trusted list
  ipv4 172.30.50.1
  ipv4 172.30.50.2
  ipv4 172.30.50.3
  ipv4 172.30.50.4
  ipv4 172.30.50.5
 allow-connections h323 to h323
 allow-connections h323 to sip
 allow-connections sip to h323
 allow-connections sip to sip
 no supplementary-service h225-notify cid-update
 fax protocol t38 version 0 ls-redundancy 0 hs-redundancy 0 fallback none
 sip
  bind control source-interface GigabitEthernet0/0
  bind media source-interface GigabitEthernet0/0
  registrar server expires max 600 min 60
!
dial-peer voice 1 pots
 translation-profile incoming INCOMING_PSTN
 incoming called-number .
 direct-inward-dial
!
dial-peer voice 30 voip
 description OUTGOING_CUCM
 destination-pattern [1-9]..
 session target ipv4:172.20.60.12
 voice-class codec 1
 dtmf-relay h245-alphanumeric
 fax-relay ecm disable
 fax-relay sg3-to-g3
 fax nsf 000000
 no vad

[Nathan Compton]

It is possible T38 isn't playing well with the PRI.  You could try modem pass-through on the gateway and ATA187 if T38 isn't necessary.

Also, sometimes these commands are needed, but not always, so I would consider whether these fax commands under the dial-peer are necessary:

fax-relay ecm disable
 fax-relay sg3-to-g3
 fax nsf 000000