DTMF sending attempt failed by GSM mobile phone over PSTN dial tone using asterisk -

DTMF sending attempt failed by GSM mobile phone over PSTN dial tone using asterisk -

i using openbts software , extends connectivity gsm mobile. there asterisk 1.8 openbts software, acts proxy , pbx route gsm calls different networks pstn using voip- gateway. please understand setup cannot upload image of setup.

there asterisk 1.8 giving proxy/pbx back upwards openbts. i can create calls mobile or sip phone landline phone through pstn using voip-pstn gateway. when dial voip-pstn gateway using gsm mobile , extends pstn dial tone on device (gsm or sip phone) then can (send dtmf digits) dial landline phone number found calls

the problem 1. not successful in sending dtmf digits on pstn dial tone using gsm phone

question: 1. why dtmf digits sent mobile not recognized asterisk. gsm uses out band (rfc 2833) dtmf signalling, pstn dial tone requires in band. responsibility of asterisk matching. why asterisk not doing matching here. setting in asterisk missing?

please give hints, problem dtmf related configuration described in asterisk 1.8?

advance all

pk srinivasan

mobile asterisk gsm dtmf