PSTN SWITCH OFF
Colt continues to support ISDN services. Everything you need to know ahead of the PSTN switch-off.
All operators, including Colt, are modernising their voice infrastructure and are moving to IP. In contrast with most other providers, Colt has no plans to end ISDN services at present and will continue to support the market by offering an ISDN over IP solution.
For customers that still require ISDN using a TDM PBX, Colt offers “Voice Line (v)”, an ISDN over IP service, which provides a seamless upgrade path to SIP Trunking on a future-proof platform.
Colt aims to help as many customers as possible to migrate swiftly to futureproof solutions – a change which is largely transparent and requires little to no physical adaptation at customer sites, apart from the installation of the Colt Voice Gateway next to the PBX. Customers can retain their access to the ‘PSTN’ with their traditional PBX while Colt ensures the network is future proof across all operators. The service is offered in the following European countries: Austria, Belgium, Switzerland, Germany, Denmark, Spain, France, Ireland, Italy, The Netherlands, Portugal, Sweden and the UK.
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WHAT SERVICE IS RIGHT FOR YOU?
Of course, Colt also offers pure VoIP with Cloud Voice and SIP Trunking solutions. If you cannot make up your mind about which solution is most beneficial for your now, see below:

Get an overview of Colt's Voice and Collaboration portfolio
OTHER SERVICES
In order to maintain the highest levels of availability and service for our customers, Colt is continuously optimising its network. Colt has recently removed SDH technology and migrated customers to newer and highly reliable Ethernet, IP and VoIP technology alternatives.
For more information see https://www.colt.net/products-services/.
PSTN FAQ
UK TIMELINES
Nov 2017
Switch-off announced
BT Openreach announces its intention to switch off the PSTN in 2025.
Dec 2020: Stop-sell trial begins
Stop sell begins at Salisbury trial site.
Oct 2021: Stop-sell expanded
Stop sell announced at 169 Exchanges across the UK.
Dec 2022: Switch-off begins
PSTN is completely switched off at the trial site.
Sep 2023: UK-wide Stop-sell
All PSTN and ISDN services will be closed to new customers, and there will be no upgrades or new features available for existing customers.
Dec 2025: PSTN & ISDN switched off
PSTN and ISDN services will be switched off across the whole of the UK.
FRANCE TIMELINES
Nov 2018: Stop-sell of analogue lines
Continued support of existing lines
Nov 2019: Stop-sell of ISDN services (RNIS)
Continued support of existing T0 (BRI) and T1 (PRI) lines
2023: Technical end of life of PSTN network (RTC)
Gradual migrations to VoIP, phased per geo zones.
REQUEST A QUOTE FOR VOICE LINE (V)
Your choice of communications service is as unique to your business as your voice requirements.
We'll ask you for a few pieces of information to request a quote in less than 2 minutes.
How many interfaces do you require for a single site?(Required) Note: Colt can support more than 10 PRIs, and they can be combined with BRIs across the same internet access but require separate voice gateway installations. In case of multiple sites, a voice gateways per set of interfaces with your PBX is required per site unless a hybrid TDM-IP device is in place.
In which country is the service required?
Any additional information? While typical SIP Trunking features are offered, please consider some rare TDM features may not be supported. These are listed in the technical specifications above.
QUESTIONS? WE'RE HERE TO HELP.
Speak with one of specialists today. We’re here to offer advice, provide further information and to answer any queries you may have.

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