Inbound/Outbound PSTN calls stopped working in OCS 2007 R2!

I encountered this problem 2 years ago and I posted it in MS Forums to look for answers. I'd just like to share how it was resolved. The architecture is like this...

Tel/Mobile Phone <----> PSTN (Telco) <--E1R2--> AudioCodes MG1K <----> OCS 2007 R2 Mediation <----> OCS 2007 R2 Front-End <----> OC 2007 R2

How was it solved? Click here... :)