Dinstar dwg2000e dtmf issue

Hi, I’ve dinstar dwg 2000e GSM Gateway. I configured 8 GSM port trunk with elastix, and few SIP trunk on elastix. the problem is with dtmf, i’ve configured DISA with 4 digit PIN (‘1845’ for example). and some of the gsm provider card work great, but some of them dont. they miss one or more digit from it. when i try to provide PIN from test phone it comes disfigured. ‘145’, ‘185’, ‘15’ or like this. dtmf standart i using is RFC2833. so how i can do this work?

another problem is that voice quality is bery low from gsm to elastix and same the back. (when i call to voip number that i configured on elastix, the quality is best but from gsm to elastix is bad.