Hello Mate,
I am the former employee of ASTPP and done many customization and integration along cgrates with opensips.
Majorly we used Freeswitch,lua and php also we having our own switch and mobile sip dialer.
If you have any questions then freely can ask us and we will answer you.
For quick chat we are available on Skype : Sam. Netcitrus
Awaiting for your reply.
Thanks and Regards
Sam