hi ASAD MAHMOOD KHAN
Our voise/speech is 3Khz, The PCM encodes 8 bit words and do 8000 sample/sec, so we get 64Kb/s.
The choosen E1 or T1 is related to capacity, regulation and network. For example if your country has been chose E1 for interconnection, then you also have to choose E1, if not, it might be problems follow if wrong format used. In terms of capacity, E1 is better which is 2M and T1 is less than 2M.
I’m not have any exprience if T1 connect with E1. But logically it will problem expecially with CIC(circuit identity check) arrangement. CIC have to be same between other’s MSC.
I think that’s all, hope it can be as a guide for you.