Telecoms Bulletin - Client Line Identifier (CLI) Issue

We have seen a recent rise in failed calls that has seen an issue with matching the voice call with the client record.  

The issue involves the last three digits of the Client Line Identifier (CLI) for alarm calls being replaced with "000," preventing the ARC system from correctly identifying the associated alarm. This leads to misidentification or unidentifiable calls. The issue has been reported across multiple SIM providers, alarm types, and ARC platforms, with providers in Wales and England seeing similar issues. 

The Digital Office is continuing to work with SIM provider, CSL, alarm manufacturers, and Telecare Service Providers to understand which existing alarms/SIMs are impacted by the CLI issue. To date we have only seen evidence of this affecting SIMs with the prefix +88 and +46. However, CSL have advised us that other prefixes could see the issue too.  

In parallel to this, to reduce the impact of the issue, the Digital Office recommends that Telecare Service Providers ensure that any NEW alarms they buy, or install are not going to be affected by the CLI issue.  If you are purchasing new devices, we recommend including a requirement that the manufacturer ensures they are not equipped with SIMs that could be affected by CLI truncation. 

Suggested wording for this is as follows; 

“A recent issue has been found where the phone number associated with an alarm’s SIM card is not passed correctly to the ARC.  In some cases, the phone number presented to the ARC is being changed, with the last three digits being deleted and replaced with three ‘000’s. This means the call handler can have difficulty identifying the Service User. To ensure the correct operation of alarm devices the alarm supplier is required to ensure that any SIM provided with the alarm is not impacted by this issue.  

Manufacturers are required to detail the type of SIM provided with the alarm, the format of the phone numbers (MSISDN) used, and how they have ensured that these are not impacted by the CLI issue highlighted above. 

I would be grateful if you could confirm what your position is with regards to the SIM installed in your devices.” 

The Digital Telecare team will continue to work with affected Telecare Service Providers and the Communication providers on this issue and give progress updates to the sector.