If you’re a network provider the idea of the new converged infrastructure where everything from voice, messaging, on-demand TV and broadcast services are provided through one channel i.e. your IP network, is probably your ideal way of delivering services. But with so many legacy systems still in use, will the change work for everyone?
From a technology point of view having to maintain old legacy equipment alongside contemporary IP networks is costly and inefficient. IP can do the job of both the old and the new. By converging all services onto one platform it creates savings and is more efficient.
However the network still has to support legacy equipment owned and used by customers. For example fixed line telephones, fax machines, ISDN PABXs, credit card terminals, analogue modems, textphones and legacy video conferencing systems all rely on this circuit-switched infrastructure.
But before we kick out the old and bring in the new, we should remember many users still rely on these devices which have been quietly and reliably doing their job for the past few decades.
The move to a converged infrastructure may allow network operators to ultimately remove their legacy circuit-switched apparatus, much of which is reaching the end of its serviceable life, but unless you can deliver a service for the consumer which is as good, if not better, network operators could find themselves with an increased number of complaints.
It’s not just the consumer who might take an interest in the switchover – particularly during the transition period. The regulators will want reassurance about service quality and price. Questions will be asked if your landline suffers audio issues when you are streaming your favourite TV programme.
With this in mind, network operators are turning to various types of adaptors. Often deployed as Customer Premises Equipment (CPE), these devices talk to modern switching systems via contemporary packet-switched networks on the provider side. At the same they are also providing legacy telephony interfaces on the customer-facing side. These are used to bridge the technology gap between modern networks and legacy equipment.
These devices have a difficult job – they must provide interfaces that are functionally identical (logically, operationally and electrically) to their circuit-switched predecessors while often using nothing but an IP-based uplink to do so.
Given that the last generation of legacy networks have set the bar extremely high with regards to things like call set-up time, audio quality and deterministic operation, how do these new devices behave?
Does a voice call end the instant its simulated PSTN line goes on-hook? Can a textphone establish a modem connection? Is the video data from an ISDN30 video conferencing system conveyed across the network correctly? Is the audio from a remote studio session using an ISDN audio codec glitch and jitter-free? Do many simultaneous calls from a simulated PRI line all create an appropriate billing record? Is the analogue caller ID presented correctly to a display equipped phone?
What’s more, whilst regulation has yet to fully catch up with modern packet-switched services, the frameworks around legacy offerings are both mature and strict.
It’s not just a regulation issue but one of finance too. When does the clock start in terms of billing? If it takes an additional half a second between the call being picked up and hearing the person on the other end speak, this is a potential loss of revenue. Conversely charge too soon i.e. before the connection is made and operators could be accused of overcharging – a misdemeanour which will put them in front of the regulators.
The only way to a smooth transition, keeping both the customers and regulators onside, is to ensure metering and billing accuracy, compliance and network reliability. That means not just metering calls but making sure when the so-called accurate measurements are based on the correct calibrated figures. If not the sums simply won’t add up.
At Roscom our design engineers have been looking at the issue for some time with our Osprey and Merlin platforms. Both can exercise the new CPE device as well as their integration with the telco’s IMS (IP-based Multimedia Subsystem) to ensure the old and the new can work together seamlessly.
No-one likes change. But if you keep in mind your obligations to the users of the technology as well as your desire to update it, you stand more ensuring the new converged infrastructure is a win/win for everyone.
Mandy Blackburn, Operations Director at Roscom.
