Ofcom has introduced changes to from the 1st October 2018 on the handling of CLI.
What is CLI?
Calling Line Identification (CLI) data consists of a network number that identifies the callers' network and a presentation number with optional privacy marking, which indicates whether an additional number can be shared with the recipient of the call. Ofcom has introduced changes to networks from the 1st October 2018. CLI Data can also be used for other functions, such as call tracing to identify the sources of nuisance calls or as a reference to help identify the location of a caller in emergency situations. For this to work effectively, the CLI Data must be accurate.
Ofcom has introduced the 08979 range for networks to use where no valid Network Number has been provided. The 08979 range is not a dialable number range should not ever be presented to the callee.
CLI Consists of the following fields:
CLI Field | SIP Header | Description |
| Network Number | P-Asserted-Identity | Not Shown to the Callee, invalid CLI re-written to 08979 |
| Presentation Number | From | Displays Callers CLI or 'Withheld' any CLI must be a real dialable number for the originator |
How does VoiceHost handle CLI?
Network Numbering: For the ingress, VoiceHost customers can already reject calls with malformed or missing network numbers. This option is found in the 'Call Restrictions' section of 'Telephone Numbers' within the control panel. For Egress routes, VoiceHost allocates a CLI 0843 into all accounts as standard and unless an alternate CLI exists.
Presentation Numbering: VoiceHost allows customers to present numbers' that are not allocated to their VoiceHost accounts by completing a presentation request. This involves the end user providing a current (last calendar months) bill in the subscriber's name showing the number to be presented.
Protecting VoiceHost Customers: We will not allow calls into our network to present excessive revenue generating types (09 and 070). These Inbound calls will be marked as number 'withheld'.
Do I need to do anything?
If you are Hosted PBX customer then do not worry as it's business as usual. SIP Trunk customers should submit spoof requests for any numbering not within their accounts to ensure the desired numbers can be presented beyond the 01/10/2018.
Further Reading
- The VoiceHost number presentation/spoofing guide can be found here: https://www.voicehost.co.uk/help/telephone-number-presentation-or-spoofing
- Further reading can be found via the Ofcom website: https://www.ofcom.org.uk/consultations-and-statements/category-2/guidelines-for-cli-facilities
