[Serusers] Granstream AtA g729 codec --- help please

Hi SER users, Iam using SER-0.9.6 with mediaproxy-0.5 and every think works fine except with the codecs . G711 a & g711 ulaw works fine but when i tuned grandstream settings to use g729 codec for pstn calls the call is not done by the Mediaproxy server . but when i created a g729 fake rtp generator it looks fine in sessions.py . so in order to forward the g729 phone call in to the pstn world what i have to do ?. Some folks told that "integrate SER with Asterisk Works!" is it really works for me? my pstn provider supports all codecs . ofcourse iam working in that company itself. please suggest some thing , so that I can bye pass this problem. Thank You. Regards, Ravi.