FAX works fine on the ATA187, with T38. However the postage loading machine (modem), does not work on the ATA187. I use Port2 with Fax Passthrough configuration.
On the PSTN gateway I have the following config:
voice service voip
fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback none
h323
emptycapability
modem passthrough nse codec g711alaw
With dial-peer debug and ISDN q931 debug, I can not see any calls coming from the ATA, so I guess there is something going wrong on the ATA.
I know the ATA186 can handle these analog modem machines for postage loading.
Here is configs on a ATA 186boxs that made it work. (however these settings are not available on the ATA187, the picture on the end below):
