TCAP is key to supporting a wide range of essential services in the mobile network, from roaming to subscriber authentication and service access. Deployed alongside today’s interfaces, like those in the 5G SA architecture, it’s essential to ensure that your TCAP operations perform as expected – and are protected against threats and vulnerabilities. Find out how you can do this, for all your mobile networks, from a single platform.

TCAP supports complex mobile network service interactions

TCAP — Transactions Capabilities Application Part — is a layer in the SS7 protocol stack that plays a vital role even in today’s communications networks. While it’s been with us for many years and, to some extent, its role has diminished, it remains key to supporting services like roaming, as well as operations in the mobile core for legacy networks. As such, TCAP is widely deployed, and many critical functions depend on it.

TCAP has always been seen as the slightly mysterious member of the SS7 family. ISUP — ISDN User Part —which has largely been replaced in modern fixed and mobile networks by SIP, is well-known, because it really handles user sessions, so it’s relatively easy to understand. A call is initiated, it’s answered, it’s closed – ISUP handles these procedures and the eventualities that can surround them.

TCAP, on the other hand, is concerned with dialogues. That is, it’s used to obtain and convey information about a user service or session. So, for example, if we want to translate a non-geographic number to a geographic number, we need to interrogate a database to find the information needed to make the translation and then complete call routing.

Similarly, if we want to know the location of a mobile subscriber, or authorise a roaming session, then again TCAP plays a role. The complexity comes, not just from the fact that TCAP messages are encoded (and so not easily understood by the casual user), but because TCAP also support higher layer protocols, such as MAP (Mobile Application Part) and CAMEL (Customised Applications for Mobile Enhanced Logic, or Camel Application Part — CAP) which perform important functions to manage user mobility, authentication and roaming in mobile networks.

TCAP initiates the dialogue, obtains the relevant information, and then closes it. It can support multiple dialogues at the same time, which means the TCAP layer can convey significant amounts of information and dialogue sessions.

Still widespread and fundamental to subscriber experience

So, it’s a kind of nest, in which you find other important information. ISUP, as we noted, is less commonly used today as IMS and SIP have largely replaced the old mobile core from 2G and 3G, but although Diameter supports similar operations in the home network, roaming traffic still depends on CAMEL, so TCAP remains essential and widely deployed.

Today, SS7 TCAP remains fundamental for many operations, but it is of particular importance for roaming. This impacts mobile subscribers, as well as devices that cross borders – trackers, for logistics, perhaps, as well as many more use cases.

As such, MNOs must be confident that their TCAP-based roaming services perform as expected – which means deploying solutions that can provide the necessary functional and performance testing, to prove TCAP system capabilities. And, assurance doesn’t stop there – because TCAP carries highly sensitive information, attackers have targeted SS7 links to undertake fraudulent activities.

Active monitoring, performance and functional testing – assure your TCAP-based services

This is where active monitoring can help. While performance testing is a regular and routine function, it’s not continuous. Active monitoring involves the insertion of software-based agents into the network that emulate real user devices and their behaviour. They can be run on a continuous basis, so that means that active monitoring agents can continuously run scenarios and use cases that emulate TCAP behaviours, providing real-time validation from the network to assure service integrity.

The GSMA has defined standards that provide templates for procedures that can be run to protect networks. MNOs need to regularly (and continuously) run these protocols, so they can defend their customers and their network partners from threats, which can emerge at any time.

TCAP, then, may be little-known outside the MNO community, but it’s central to huge amounts of traffic that must be processed, both within and between networks – and, of course, the network edge and interconnection points are the most vulnerable and most targeted elements.

Legacy SS7 and modern interfaces, like 4G and 5G NSA / SA in a single solution

Emblasoft Evolver is a complete assurance solution that provides functional and performance testing, as well as active monitoring capabilities. It supports legacy TCAP – as well as the higher layer protocols, such as MAP, CAP and INAP. Not only does it offer full support for the SS7 family, but it also supports 5G SA / NSA interfaces, Diameter, SIP and a host of other crucial interfaces. You can read a comprehensive list, here.

Users can integrate their assurance programmes with this single platform, spanning legacy connections as well as their 4G and 5G networks. The combination means that MNOs that have been using dedicated platforms for legacy networks can retire those and converge on a single solution that allows simultaneous delivery of complex test and active monitoring procedures, fully integrated with automation platforms and solutions.

Evolver provides the capabilities you need for all your networks, offering ease of use and powerful functionality and scripting to cover any scenario. If you’d like to know more, get in touch!