We have an engineer who resides in Mexcio.
Our UK office has an Avaya IP Phone system which allows remote users the facility to plug an IP phone into their home / office broadban and become and extention of the UK based office.
This in turn allows us to have free call between UK and Mexcio all day long (thus saving £££ in mobile phone / land line bills).
My problem lies with one user, who supplier Telmex has a branded Cable router which will not allow you to change the IP address of the box.
As the UK and Mexico locations reside on the identical ip range of 192.168.1.1/24 range. when ever we plug an IP phone into the broadband line, it connects fine BUT all voice calls are silent.
I've opened up every port required to allow the firewalls to ignore the open ports. I've changed my home ADSL ip range to be 192.168.1.1/24 and have the same problem (so I know that it's a firewall routing problem).
Is there a way I can get this working WITHOUT replacing the Telmex Cable box in Mexico.
I have phoned the Telmex supplier but every time we change the IP, all routing in the box fails and will only work again after an factory reset.
I've been told that an Apple Airport Express can manage this BUT am I wrong ?