We have received sporadic reports, following our changes to enable compliance with the revised GC6, that some calls are arriving presenting a telephone number starting 08979 when a number that is not on your Simwood account is used as the CLI.
These 08979 numbers are assigned by Ofcom and intended to be used internally by Communications Providers to facilitate tracing calls. More details can be found here; http://blog.simwood.com/2018/09/mandatory-cli-changes/
They should never be presented to the called party as appears to be happening in isolated cases, and it's likely that the underlying issue is outwith the Simwood network where this is happening.
If you do receive any reports of 08979 numbers being presented on outbound calls, please raise a ticket with our support desk providing examples of calls this happened on (e.g. the date/time, caller ID you presented, and the dialled number)
We strongly recommend all customers use P-Asserted-Identity, and set this to a number that is on your Simwood account for all calls. You can set a different presentation number (e.g. where forwarding calls) by using the From header.
In cases where a valid Network Number / PAI has been set, then in these edge cases the customer will see this number rather than the 08979 which is a better experience (we only resort to using the 08979 if no other number is present)
You may also wish to consider using the Default Network Number option in the Trunk configuration to set a preferred Network Number.
We're confident this is affecting a very small number of calls, but are investigating this and will liaise with any terminating carriers that appear to be displaying the number incorrectly. In each case we are sending both the Presentation Number and Network Number, and they are electing to display the "wrong" one.