IP Office with Public IPs
 

i setup the IP Office 500 V2 Wan port with public IP to be able to use the Avaya IP softphone anywhere out of office with just internet connection.
this was tested in Egypt and it was working perfectly now i am in USA and i fail to make calls or receive calls.
i cannot hear anything ; when i access the trunk lines and dial anyone , they cannot hear me and i cannot hear them.
when anyone calls me i cannot hear them and they cannot hear me.
this happens from happens the same when any extension inside office tries to call me or i call them

Anyone can help?

That seems RTP & RTCP packets can't through the internet between your office and IPO. So you should check that the port of RTP & RTCP can pass the internet between your office and IPO.

how can i do this

In what realm would you "want" to put something on the public internet? Why not a VPN?
Is this in a DMZ, or is it actually on the public side of the internet?