HP Mobile Fax Error for UK Fax Number

[sgm1231]

I have a HP Color LaserJet Pro MFP M479fdw, Product W1A80A. I'm trying to use HP Mobile Fax launched from HP Smart v151.3.1092.0 on Windows 11 logged on with my HP account, however get the error "Something went wrong! It seems that an error has occurred before sending process. Please, try to send your fax again. Try again." when sending a fax to a UK number. I can use Mobile Fax with US (+1) numbers (as previously and still today) but it won't work with a valid UK (+44) Fax number. I've tried the HP test number [Personal Information Removed] successfully. I've called the UK number from a phone in Australia and I get a fax tone as expected. The Mobile Fax contact enters the UK number as [Personal Information Removed]. HP Support WhatsApp chat advised "I believe this is a fax issue I would request you to please reach out to the service provider regarding this issue as the printer is working fine with the other number." The HP Mobile Fax doco includes the UK as a valid destination. Is there some limitation with HP Mobile Fax service? My account is marked as "Standard" dashboard.

[sgm1231]

I believe the issue may have something to do with High-risk call blocking. To protect from fraudulent phone activity, VoIP phone services are blocked from making high risk calls to certain international destinations by default. As a result, some services are unable to support the sending of faxes to prefixes such as '44844' & '44845' due to carrier blocks. The UK country code +44845 is defined as a “business rate number” and a “UK Shared Cost destination”. I understand that Call Blocking for this destination cannot be removed. I have tried sending a fax to the +44845 destination via another internet fax provider and receive the specific error message “Recipient number is on blocked list”. However, with the HP Mobile Fax app the error message raised is not specific enough. The HP Mobile Fax error handling could be updated to report some specific error code if it relates to a Call Blocking issue instead of the vague error message “Something went wrong” which helps no-one in understanding the issue. I assume that HP Support would be able to confirm if the HP Mobile Fax service blocks +44845 number.