SIP ATA line as PBX trunk lines, DTMF, touch tone issue?

SIP ATA line as PBX trunk lines, not producing corrected dial out digits - DTMF, touch tone issue?

I saw one of the posted is similar to the following:

  1. line 1008 is a SIP line from SPA 2102 ATA which is connected to and registered to an Asterisk Server.

  2. plug 1008 ext to the Avaya Legend PBX Trunk/CO port, we treat the 1008 as a trunk line/POTS for one of the the PBX trunks.

  3. call 1008 got the auto-attn greeting from the Legend PBX, then dial ext. 4288 but it seems that the touch tone is not sending out the correct digits of 4288 so the call never ring to ext. 4288 (if we connect this PBX CO trunk to a Verizon POTS, and call the POST line, we would get the same greeting and also able to dial any PBX extensions - I enable the ability to dial extensions on the auto-atten greeting setup/routing and was working fine when use a regular Verizon POTS as Trunk lines)

  4. We tried to change the SIP SERVER’s DTMF from Inband to RFC2833 or even SIPINFO but the touch tone is still not dialing out the corrected digits…

Any suggestions that we can try to correct this issue?