Dear reader,

This is a post for anyone who wishes to ditch their ISDN lines for SIP but does not necessarily want to purchase a new VoIP telephone system.

When will ISDN be switched off?

BT Group CEO Gavin Patterson has set a date of 2025 to switch off ISDN services from its Public Switched Telephone Network (PSTN). BT Group are set to no longer accept any new orders or amendments to services pertaining to any ISDN product as of 2020 with the final termination set for 2025.

Is VOIP telephony a sensible alternative to ISDN?

HELL YES!!! one it's cheaper, ISDN channels tend to cost in the region of £12-15 per channel whereas SIP trunk channels are around £5-6 per channel, so effectively cutting your fixed line monthly cost in half. Second we haven't really got a choice. BT are slowly phasing out ISDN2 and ISDN30 to bring the remaining outlying customers on to the single core IP network as soon as possible. This presents an opportunity for SIP and VoIP providers to challenge BT for the business.

Two types of VoIP Telephony

1: Hosted VoIP (off premise)

Hosted VoIP as the name suggests is totally cloud based with added functionality and reduced call costs. With hosted VoIP there are no additional maintenance charges. Each user has their own DDi line and calls are routed through the internet with free calls between on-net users. However this is an ongoing monthly charge so not always the best fit for a small company looking to reduce their monthly overheads.

2: SIP Trunks (on-premise)

Similar to traditional telephony, you will have a on-premise telephone system but route your calls using SIP trunks rather than ISDN channels.

How to migrate onto SIP trunks cheaply

Businesses that still use ISDN can switch comfortably and quickly to SIP trunking or hosted VoIP, with or without BT, as numbers can be ported and retained and the whole service can be set up within weeks. Now what a lot of telecommunication providers will not tell you is that you can convert any existing PBX telephone system to work on SIP trunks by installing a Gateway box.

What is Gateway

Gateways are a small piece of hardware that sits between your ISDN lines and your telephone PBX (or switch). Gateways can convert your analogue ISDN signal to a digital signal for a VoIP system to receive, they cost around £400-800 depending on the number of available channels required. BUT and this is the golden egg, which telco companies will not usually share with you as they would prefer to sell you a new telephone system instead of just upgrading you to SIP. Gateway boxes work in both directions so you can also connect them to your newly installed SIP channels and the unit will convert the digital SIP channel signal back to an analogue signal for your old existing analogue PBX to work just fine.

So in summary

It doesn't matter what your current onsite telephone system is, whether it be VoIP enabled or not, you can still benefit from the reduced ongoing monthly savings of moving away from ISDN and onto SIP trunks by utilising a cost effective Gateway unit.

If you have any questions around this i am more than happy to help.

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@neuroevolution