Build or buy a GSM HLR? Is there an alternative?
The classic question in IT is to buy something existing or to build it from scratch. When wanting to buy an off the shelves HLR (that actually works) in most cases the customer will end up in a vendor lock-in:
- The vendor might enforce to run on a hardware sold by your vendor. This might just be a dell box with a custom front, or really custom hardware in a custom chasis or even requiring you to put an entire rack. Either way you are trapped to a single supplier.
- It might come with a yearly license (or support fee) and on top of that might be dongled so after a reboot, the service might not start as the new license key has not been copied.
- The system might not export a configuration interface for what you want. Specially small MVNOs might have specific needs for roaming steering, multi IMSI and you will be sure to pay a premium for these features (even if they are off the shelves extensions).
- There might be a design flaw in the protocol and you would like to mitigate but the vendor will try to charge a premium from you because the vendor can.
The alternative is to build a component from scratch and the initial progress will be great as the technology is more manageable than many years ago. You will test against the live SS7 network, maybe even encode messages by hand and things appear to work but only then the fun will start. How big is your test suite? Do you have tests for ITU Q787? How will you do load-balancing, database failover? How do you track failures and performance? For many engineering companies this is a bit over their head (one needs to know GSM MAP, need to know ITU SCCP, SIGTRAN, ASN1, TCAP).
But there is a third way and it is available today. Look for a Free Software HLR and give it a try. Check which features are missing and which you want and develop them yourself or ask a company like sysmocom to implement them for you. Once you move the system into production maybe find a support agreement that allows the company to continuously improve the software and responds to you quickly. The benefits for anyone looking for a HLR are obvious:
- You can run the component on any Linux/FreeBSD system. On physical hardware, on virtualized hardware, together with other services, not with other services. You decide.
- The software will always be yours. Once you have a running system, there will be nothing (besides time_t overflowing) that has been designed to fail (no license key expires)
- Independence of a single supplier. You can build a local team to maintain the software, you can find another supplier to maintain it.
- Built for change. Having access to the source code enables you to modify it, with a Free Software license you are allowed to run your modified versions as well.
The only danger is to make sure to not fall in the OpenCore trap surrounded by many OpenSource projects. Make sure that all you need is available in source and allows you to run modified copies.