Hey UC Pros! The need to interoperate across organizational and logical borders with different numbering requirements exists since the very beginning of the digital telephony. Whether you interconnect with a SIP ITSP or your own legacy PBX, you will likely need to manipulate digits you exchange on both ends. In Cisco IOS (and IOS-XE later) running either CUBE or Voice Gateway, Voice Translation Rules and Profiles come to a play to help you get things done.
In this article, we are going to demonstrate how this powerful feature works in general and how it applies to most common interoperability scenarios in real UC world.
Connecting the Cisco IOS Voice Gateway to CUCM via SIP has been the preferred way to do it in the past couple of years.
The slowly dying H323 protocol (ISDN based) is not being developed anymore while SIP (HTTP based) became the industry standard for VoIP. So whenever PSTN connection is implemented via an IOS Voice Gateway, the choice should be really between SIP & MGCP.
There is no way around it, finding the SIP call flow is the first thing you have to do when you are facing a SIP call failure.
Why? Easy. Because first of all, you have to understand whether this is a call routing problem or signaling/media compatibility issue. SIP call flow helps you understand just that, and in a lot of cases, you can pinpoint the problem just from looking at the SIP call flow.
Prime Collaboration Assurance deployments (PCA) became very popular since Cisco has started giving it away for free (standard version) with new orders. It is indeed a great tool for those who are willing to make the effort and make it so. Are you?