How to develop my own VLR Number Lookup system using SS7 protocol?

Question

I have been in a project which need to know the user last location from VLR(Visitor Location Register). I have seen many online SMS providers offer a special service called HLR Lookup. Some websites offer VLR lookup e.g txtnation. VLR lookup may be possible by using the flaw of a poor design choice of the Signaling System No. 7, the global network that powers your calls, in which all GSM operators tap to communicate with each other.

SS7 is really old, and nobody bothered to replace it as technology advanced in the GSM world. It is quite impossible to replace/disable/remove it now because everything is based on it.

MAP Signaling is an SS7 protocol that provides an application layer for the various nodes in GSM. Yate is a partial open source implementation of MAP.

But there is not any service for getting VLR response. So would you please advice me

• How could I create my own VLR lookup system?
• What type of resource I need to develop this system e.g server
• Is it related to VOIP? Should I need to setup SIP server?

Thanks a lot in advance.

Answer 1

Firstly, I think that the service you have linked to is really just providing a HLR lookup rather than a VLR lookup from a quick look at their API - i.e. there does not seem to be anything returned by the API which a regular HLR lookup would return.

It would also be odd for a carrier to allow communication to a VLR directly from an entity outside their network - this is not really what the VLR were intended for.

To create a HLR lookup service, the most important thing you need is the access to some operators SS& network, or else to a service that will proxy SS7 requests and responses from you.

If you have this access then building on an opensoure SS7 gateway would seem a sensible starting point, for example a SIP-SS7 gateway as I think you suggest.