HLR LOOKUP service building

Question

Newbie here. Can someone teach me like im 6 years old? How can I do my own hlr lookup without paying a companies? I see some people send some company links who offer hlr lookup.Thats not what I'm looking for... I made some research and couldn't find much about how can I build a hot lookup. Any help would be great.

Answer 1

Hi sdaassadasdasd asdasdsad,

TL;DR you can't perform your own free HLR lookup against telephone numbers on the public telephone service (formally called the PSTN), which is why you can find online providers who provide it as a paid service. There is always a charge, even to the HLR lookup providers.

It also depends what do you want to achieve. A HLR Lookup will let you know if a mobile phone number is assigned to a subscriber of a mobile network operator (MNO), and which MNO it is assigned to.

HLR lookups don't provide location (aside from some rudimentary country-wide location based on the Mobile Switching Centre that the telephone handset is being controlled from). They also don't usually provide an IMSI if that's what you are looking for, because these days most MNOs will implement home-routing which gives a temporary IMSI matched on their router so that they can conceal the real IMSI (to avoid fraud).

So, if you do want to perform a HLR lookup to check if a mobile phone number is "real" and assigned to a subscriber on a public network then I'm presuming you want to send a HLR request to query an external MNO - i.e. a public telephone number, not a local one running on your own equipment.

To query an external MNO then you will need to send a request, usually over the SS7 network, to the mobile network operator who was originally assigned the telephone number you want to know about. Eventually, if you have done everything correctly and the MNO wants to respond, you receive a response back which gives you the details you need to then ascertain if the telephone number is assigned to a subscriber, and if the subscriber is active on the network or not.

To send the HLR request, without going through an online provider, you will need at least:

• equipment that talks the SS7 protocol (specifically to include MAP requests because a HLR is a type of MAP request)
• somewhere to host your equipment
• an SS7 interconnection from an SS7 backbone provider
• point codes allocated from the SS7 backbone provider
• someone to setup program the equipment
• your own telephone prefix range for the far-end MNO to be able to respond back to your original request. You may be able to lease someone else's telephone number range if you don't have your own.

Once everything is setup then there's an additional per MSU (message signalling unit) cost. You can think of an MSU a bit like an IP packet, you send "one" and you get a response. You are charged by the SS7 backbone provider for every MSU you send that transits their network, regardless of if you get a response back from the MNO you want the message forwarded to.

I'm happy to answer any other questions on it, but I can't think of a way you can perform your own HLR lookup without incurring charges somewhere along the line.