I’ve been deploying a lot of CUBE environments of late with faxing working from the T.38 protocol. I did want to jot something down regarding faxing to the PSTN via ISDN using an ATA190 registered to CUCM (doesn’t really matter what version) and connected the Voice gateway via a SIP Trunk.
I’m based in Australia and the fax settings I’ve found to be most successful as follows.
ATA190 Device Configuration page in CUCM
- Ring Voltage = 70V
- Ring Frequency = 25Hz
- Fax Mode = NSE Fax Pass-through g711alaw
Voice Gateway (Cisco IOS)
Under the Voice Service Voip Menu.
- modem passthrough nse codec g711alaw
CUCM SIP Trunk configured as per normal, no special configuration. I have aLaw configured, I found uLaw (which is also acceptable in Australia) was working for outbound faxing but not for inbound faxing, however I have had some case where the opposite is true.
Just a matter of making logical/strategic changes to the faxing configuration to ensure both directions are operating correctly.