FAX Setup Over SIP

You may encounter FAX issues when you convert PRI to SIP. Few steps to troubleshoot FAX related issues

1- From CUCM/ ATA side we need to make sure T.38 FAX Relay is selected

2- ATA following should be selected

3- CUBE Side

voice service voip

fax protocol t38 version 0 ls-redundancy 0 hs-redundancy 0 fallback pass-through g711ulaw

no fax-relay sg3-to-g3

4- Dial peer add following commands

fax-relay ecm disable

fax-relay sg3-to-g3

fax rate 14400

fax nsf 000000

5- Make sure on CUCM Region is properly configured. If ATA and CUBE are in two different Region, Make this two region codec is properly added.

6 -  CUBE you could enable following debugs to see what's happening for fax inbound and outbound

debug ccsip messages

debug voice ccapi inout

debug fax relay t30 all-level-1