As communications networks evolve, interconnects tend to grow in numbers and complexity. Carriers and enterprises are converting core networks to IP, and are using IP to con­nect with peering entities. For the network core to deal with the emerging universe of applications, networks and devices, those elements must first be normalized at the edge. Through intelligent edge technologies, traffic must be inspected, under­stood, converted and routed – so that every internal system does not have to deal with every potential possibility.

To gain the simplicity needed in this complex network environment, advanced SBCs (session border controllers) now function as the Rosetta Stone – or language translator – of the modern com­munications network.

A Smarter Edge: Software Everywhere

Carriers must deploy intelligent controls and policies needed to seamlessly normalize and interoperate with multivendor and multiprotocol devices across different networks – fixed and mobile IP networks; different standards – NGN, 3GPP IMS, Packet Cable; different transport mechanisms – UDP, TCP, SCTP, TLS, IPv4, IPv6, RTP, SRTP; different protocols – SIP, SIP-I, SIP-T, H.323, MSRP, DIAMETER, RADIUS, ENUM and different media formats - G.711, G.729, AMR, iLBC, EVS, DTMF.

All that – while delivering consistent, advanced, high definition multimedia services to carrier partners, enterprises customers and residential subscribers.

An intelligent approach to session border control provides transparency via dynamic message- based scripting to manipulate SIP header and message bodies in real-time, dynamically reacting to SIP responses and optimally determining the need for media normalization, thus ensuring smooth inter­working between a large and diverse ecology of suppliers and partners across interconnect and access networks.

Easier Said Than Done: SIP ≠ SIP

When it comes to session interworking challenges, no two applications are same.

IPX (IP Exchange): Ensuring Seamless Multi-Carrier Interconnects

SIP comes in many variants: Non-IMS SIP to interconnect with fixed IP networks, IMS based SIP to interconnect with VoLTE networks, SIP with encapsulated ISUP (SIP-I or SIP-T) to interconnect with TDM networks.

In the case of IPX networks, there are many international variants of ISUP requiring support.  ISUPs gets encapsulated in SIP message bodies using either SIP-I or SIP-T protocol depending on whether the communication is between SIP and PSTN network or from mobile softswitch to softswitch.

Interworking between SIP to SIP-I and SIP to SIP-T is one of the most complex challenges and continues to create new hurdles as SIP evolves. Though IP interconnect carriers should agree on a SIP profile to be used for interconnection, they must also deploy an intelligent SBC solution that provides the flexibility to resolve SIP interworking challenges in real-time by leveraging solutions such as flexible SIP message manipulation.

SIP Trunks: Ensuring Seamless PBX Interworking as Business Communications is Transformed

Service providers delivering SIP Trunking services to SMBs (small and medium size businesses) and enterprises are challenged to assure interoperability across multiple PBX types and even be­tween revisions of software on the same PBX. 

Codec mismatch, one way audio, incoming call transfer failure, trunk registration failure, and DTMF mismatch are all examples of interoperability challenges service providers and enterprises face in migrating from PRI to SIP Trunks. 

The entire ecosystem is continuously evolving. Service providers are hard-pressed to stay ahead of the curve as SIP specifications are augmented, new products and software revisions are released, and new vendors enter the fray. To make matters worse, enterprises routinely upgrade IP PBX releases without notifying the SIP Trunking service provider. 

Maintaining on-going interoperability can be very cost and time prohibitive and impacts market reachability and time-to-market.

The SIP Forum has done a tremendous job in crafting the SIPConnect standard to reduce PBX interoperability challenges. Though it is certainly a best practice to conform to this standard, define PBX interop templates, create your own configuration guides to avoid misconfigurations, and regularly test with PBXs; there is always an anomaly out there, especially with a penetration of open source PBXs. This is breaking the service when the services is needed most.

The use cases are endless – Cloud UC, VoLTE, RCS applications, OTT applications, Collaboration, Call centers…they all have their unique interoperability challenges. Deploying SBCs that are equipped with real-time SIP manipulation capabilities cut this complexity and risk off at the pass.

Not all SIP Message Manipulation Solutions are the Same

SIP header manipulation capability is becoming a standard part of most carrier grade SBC vendors now; but there are diverse implementations and some are not as efficient and comprehensive as others. While it’s important that the solution enables service providers to modify the SIP messages in real-time, there are many other important characteristics to consider as SBC solutions are evaluated.

I will cover these characteristics in a future post, highlighting the gains service providers make when they make the right decision about SIP messaging and SBCs going forward.