Approaching 2025 Deadline - Expectation of Increased Call Failures

In January 2024, some Telecare Service providers experienced a higher-than-normal volume of call failures (Handshake failures). 

These failures were higher than the 1.8-2% average usually seen.  This resulted in 8718 failed calls over a two-three-week period and affected approximately 300 dispersed alarms. The vast majority of these were Tunstall telecare alarms operating on analogue STMF (Sequential tone) protocols. 

The Tunstall protocol STMF appears to have been affected by work carried out within both Talk-Talk and Open Reach networks.  This was a one-way transmission issue affecting STMF, and the network interconnection to the exchange.  As a temporary fix, Talk Talk has reroutedsome affected areas to a non-upgraded section of the network.  This appears to have fixed the issue for most Service providers.  

To mitigate the risk, actions taken by the Service providers vary and include the following: 

• A call to the Service User to reprogramme the alarm remotely to DTMF (Dual tone) from STMF. 

• A visit to the Service Users home to reprogramme the alarm from Tunstall’s STMF to DTMF protocol and it was noted that some alarms already configured to DTMF reverted to STMF (this could be due to a power failure to the alarm resulting in a factory reset).  

• A visit to the Service users' home to replace the analogue alarm with a digital device. 

• Geographical number routing within the device programming (eg, 0141, 0131) could also help reduce calls failing that may be affected by re-routing from non-geographical numbers (, eg, 0345, 0800 numbers). 

It is worth noting that a handful of alarms that had been programmed to DTMF had been found to revert to factory settings and using STMF protocols despite reprogramming.  It is unknown why this has occurred, but it could be due to a mains failure (along with a battery failure) causing the alarm to shut down and revert to STMF protocols.  

Failed calls can occur for several reasons, however, network upgrades currently being completed by telecoms providers, such as BT (British Telecommunications), Sky, Talk-Talk and Virgin Media, are thought likely to increase call failure rates. Telephony providers are all completing upgrades of their networks which will see digital lines rolled out to all customers. This process has already started and will be completed by December. 2025. Since the outage, Talk Talk has introduced monitoring of failed calls to help evaluate the impact of network changes. They have also confirmed that single tone will no longer be available on their upgraded network. 

Devices using DTMF may continue to work in an IP environment, however, there is an increase in likelihood of failure. Devices using any proprietary implementation of DTMF, such as STMF, have proven to suffer a greater likelihood of failure in the IP environment.  Further information is available here 

Further advice from the Digital telecare team would be to:

• Regularly report on failed calls and investigate increases.

• Highlight abnormal increases in call failures to the Digital Telecare team.

• Collect CP (Communication providers) information at point of assessment and at regular reviews.

• Consider leaving an alternative contact number for your ARC (Alarm Receiving Centre) on the unit or in the service user's home.  

The above are contingency measures to lessen the impact of call failures and moving to digital as soon as possible is the best way to reduce the overall risk.  

For more information on call failures, please see Play 007 Failed Calls Data Guidance in the Digital Telecare Playbook.