Re: [Request] Virtual Roaming Systems for GSM, GPRS and UMTS
I don't have 130$, though it can be found at a lower price.
Why I am requesting this book is because we discovered an interesting issue with some roaming subscribers, google gave me a little preview, where I kind of discovered the same behavior described in the book. The preview is not enough as it stops at the most interesting... Searching in the 3gpp standards but no results.
Here is the thing:
Roaming subscriber comes in visit. He wants to activate a PDP.
Facts:
1. The authentication phase is successful, gets the triplets from HPLMN HLR. Good. Communication between SGSN and HLR is based on E.164 numbering plan.
2. GPRS location update ... fails, cause: Unexpected data value (this error has no precise meaning).
But the interesting fact is that the HPLMN HLR is not using E.164 numbering, but E.214 numbering plan when announcing this error back to SGSN, and the number is permanently changing.
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