Can anyone tell me, what is the maximum number of mobile phone numbers that can be connected in a conference call and how many connected members can give same DTMF input simultaneously.

I have a requirement where I need to call 22 phone numbers in a conference call and receive DTMF input(Digit 1) from these callers at once. I tested with 17 callers, when all of these 17 members pressed 1, my esl program received only DTMF event from only 8 callers.

Just wanted to confirm if there are any sort of constraints regarding conference calls.

Regards,

Deepika