Brekeke has confirmed interoperability with many various ITSPs. Using our template settings at the ARS of Brekeke PBX, you can set up ITSP lines with Brekeke PBX very easily.

List of ITSPs we have tested:
http://www.brekeke.com/support/support_interoperability_itsp.php

Unfortunately, Skype does not currently support SIP yet, but they are working on a project called "Skype for SIP" that will allow Skype users to connect with SIP services/devices. Once Skype supports SIP, it should work fine with our products, just like the other SIP services available in the market.