Here is the debug.

Jul 1 12:34:35.482: ISDN Se0/0/0:15 Q931: TX -> SETUP pd = 8 callref = 0x47F3

Bearer Capability i = 0x8090A3

Standard = CCITT

Transfer Capability = Speech

Transfer Mode = Circuit

Transfer Rate = 64 kbit/s

Channel ID i = 0xA9839C

Exclusive, Channel 28

Calling Party Number i = 0x2081, '69363070'

Plan:Unknown, Type:National

Called Party Number i = 0xA0, '1532195069363060'

Plan:Unknown, Type:National

Jul 1 12:34:35.542: ISDN Se0/0/0:15 Q931: RX <- CALL_PROC pd = 8 callref = 0xC7F3

Channel ID i = 0xA9839C

Exclusive, Channel 28

Jul 1 12:34:35.842: ISDN Se0/0/0:15 Q931: RX <- PROGRESS pd = 8 callref = 0xC7F3

Progress Ind i = 0x8A81 - Call not end-to-end ISDN, may have in-band info

That all, no more progress or alert from isdn.

Very strange, is the called number correct ?

Yes indeed. Its a number for a particular service.

The problem I see is only related to this service. If I do a blind transfer to something else (ex. mobile, regular pstn phone), its ok. So I expect that I'm missing something from the destination switch. But I'm not sure. They say it works if they are using a Nortel og Ericsson pbx instead of CUCM/h323GW. I not that into isdn to say who is doing something wrong.

Try making a regular call to that number, and compare the isdn trace line by line.

I though I had that trace in my logs, but no. But I'm quite sure that the next message form isdn is a connect when the pstn phone/services is answered. The strange is that my ip phone is getting ringback when calling the number.

When comparing calls to a mobile phone, I normally get ALERT from pstn instead or in addition to the PROGRESS. So for sure there is a difference.

Anyway, I'll try to compare as you suggested.