ISDN is being phased out | Peach Technologies Initiatives

Important Announcement

By 2020 all ISDN lines will be phased out by BT

Migrating from ISDN to SIP with Peach couldn't be easier

ISDN has been a standard for so long that you might have concerns about moving away from a service that already gives you good call quality and flexibility. Let Peach put your mind at ease.

Like all things in the world of Technology, change is coming. By 2020 you will no longer be able to order ISDN and SIP Trunks will be in its place. We understand that many businesses may be hesitant about this move, so read on and take action sooner rather than later.

What are the benefits of SIP over ISDN?



  • Requires dedicated installation costs
  • Rental costs on average £15 - £20 per channel
  • Call costs on average can be up to 25% more expensive
  • Can use existing planned or dedicated connectivity at a much cheaper cost.
  • Rental costs usually £5 - £10 per channel
  • Free calls between sites connected on network locally and internationally


  • ISDN2 has 2,4,6,8 channels
    ISDN 30 has 8 to 30 channels
  • ISDN 30 requires sequential DDI ranges with a maximum of 5 different ranges
  • Can only increase/decrease channels with Openreach planning. Once an ISDN30 has 30 channels, a new bearer is required for additional channels.
  • SIP can have 1-2,000 channels on one connection
  • No limitations on DDI ranges
  • SIP can expand/decrease instantly


  • Can only use local geographic pre-fix numbers from the local exchange
  • Needs to be diverted by network provided and can only divert main bearer number
  • Lead time for ISDN installs can be 2-8 weeks
  • Use any geographic and international number
  • Can be diverted instantly and can divert by DDI
  • Can be delivered instantly, depending on current connectivity

Additional benefits for your business

  • Business Continuity

    Keep your business running with minimal disruption. You can be prepared for any situation, put in place a disaster recovery plan and have us set up back-up facilities. You can re-route calls instantly in emergency situations.

  • Familiarity

    If your business has multiple sites, SIP trunking can rationalise the number of PBX's you'll need to maintain, with no loss of control of your telephone numbers.


  • Is it secure?

    When SIP trunks are implemented correctly, fraud is not an issue. Connectivity will be more secure than previously. A properly configured SIP channel will allow you to handle your own connectivity via dedicated firewalls or a router with firewalls built in, which is managed by Peach Technologies.

  • Call quality won't be as good!

    SIP Trunking uses private IP connections specifically designed to carry voice, and as such come with Quality-of-Service guarantees. SIP Trunks therefore can deliver the same or sometimes even better call quality than ISDN. We provide an expert SIP service that comes with a dedicated support team to help maintain SLAs and Quality-of-Service guarantees.

  • It will cost too much!

    Upgrading to SIP will have the opposite effect, it will save you money in quite a significant manner. You’ll save most noticeably when no longer paying ISDN line rental costs. Additionally, you’ll have access to lower call rates or in some cases, free calls to UK destinations or mobiles. Typical savings can be 50% on line rentals and 25% on calls. Calls between connected sites are also free, even those that are international.

  • It's new and untrustworthy!

    SIP has been around since the mid 1990’s and SIP trunks have had a presence since 2007, the technology has been in use for some time. It is safe to say there is a substantial body of expertise in the marketplace today, and that the technology is well tested and up to date.

  • Migrating will be a hassle

    Deploying SIP Trunks is an easier process than with ISDN. Peach puts a good plan in place before you start your project. Full onsite support is provided so you won't be left to cope with any issues yourself.

  • SIP will complicate everything

    The reason businesses like SIP so much is that it helps when it comes to rationalising and streamlining telephony. This is particularly useful for companies operating on a multi-site basis. And as BT are phasing out ISDN anyway, there really is no choice in the matter.