our tests were DID call back , the use dials for a DID number having it assigned to span2, and the call back to the redirect number specified in the account information is working out without any problems, where as when the user receives the callback and gets the IVR prompt to enter his destination he enters the number for the destination he is attempting to call, but the caller fails to connect to the calling party due to the DTMF error.
Let us try to trace the problem by referring to the call flow for the specified scenario:
span2—>(smgw)acts as callback server—>smgk–>smgw—>span1—->carrier—>GSM company—>mobile phone
span2 &span1 are E1 connections
i appreciate your reply.