As a part of my job, I manage and maintain customer platform – usually operating in the Calling Cards and VoIP services market. Over the course of time, I’ve learned to rely on some providers in this world, knowing that they work 99.999% of the time.

For example, i like working with DID numbers provided by Level3, GlobalCrossing and Voxbone. I have a fair dislike for DIDX and the like, simply due to the fact that their reliability, not the DIDX platform, but the providers themselves is questionable – at best.

So, why is this post called: “Battliing the GlobalCrossing CallerID blues”? simple, because the list that appeared before is now missing GlobalCrossing. Over the course of time, I’ve learned to live with the various quirks of GlobalCrossing, mainly, their inability to provide a proper e164 number as a part of the SIP headers. Usually, I would receive headers from global crossing that look like this:

FROM HEADER: <>;tag=as54cf6928

Now, I new that in general, that didn’t post much of a problem, as long as it was consistent. However, starting today, some of the requests started looking like this:

FROM HEADER: <>;tag=as1213141

However, to make things weird, one INVITE request would carry the non-valid e164 numbering, while the second INVITE may carry the correct format. In other words, there is no way to know exactly if the number is provided in full e164 or not. So, I tried doing some header mangling using Asterisk and other tools, however, nothing helped. Surely the format changed along the way, however, when I changed one side of the system, another side of the system broke – simply because it relied on something else – in other words, a fuck’n mess.

At this point, the problem is not yet resolved and i’m working with my DID provider to remedy the situation – after investigating it, the DID provider is currently bashing the heads at GlobalCrossing to fix the issue on their side. I will report back once I have more information.

If you suffered similar problems with other DID providers, I’d love to hear about it.