This has been tricky, because there are rules on 07 mobile numbers. The specific rule is part of the OFCOM National Numbering Plan. In particular the definition :-
‘Mobile Service’ means a service consisting in the conveyance of Signals, by means of an Electronic Communications Network, where every Signal that is conveyed thereby has been, or is to be, conveyed through the agency of Wireless Telegraphy to or from Apparatus designed or adapted to be capable of being used while in motion;
But it gets interesting. The rule on the use of numbers is :-
Those to whom Ofcom has Allocated any Telephone Number listed in Part A of the Plan shall not Adopt or otherwise use it, except in accordance with the applicable designation given in Part A for that number range.
The good news is that we are not someone that has been allocated the numbers we are using for this (by OFCOM). The existing mobile operators are the ones that have been allocated these numbers by OFCOM. So categorically we are not breaking any rules here.
The question comes when considering if OFCOM will be unhappy with the mobile operators providing a service to us. Well, for ported in numbers from other networks than the one we are using, again, they are not the one allocated the number by OFCOM, so for ported in numbers they are OK as well - yay. The original network has to allow porting, and so cannot do anything, so they are in the clear.
But what of numbers allocated by the operator we are using?
Well, we have tried very hard to get OFCOM to answer whether they have ever enforced this rule on 07 mobile numbers. We see, every day, that all of the mobile operators break the rules, and OFCOM have confirmed no exceptions have been granted but no enforcement has been taken. I even pursued an FoI request.
But look at the reason for the rule - once upon a time mobile calls cost a lot, and if the calls did not use the Wireless Telegraphy to or from Apparatus designed or adapted to be capable of being used while in motion then it was a way of operating a sort of premium rate number without the normal rules on such things. These days the cost of calling a mobile, and importantly the terminating revenue, is really low (not quite as low as landline, but low enough not to make sense for that loophole). So there is no reason for the rule anyway.
Every operator allows calls to mobile numbers to go to voicemail. That is against the rules.
Every operator allows divert to landline. That is against the rules.
Some operators run call centres on their 07 numbers. That is against the rules.
Some operators allow wifi calling, which can be used over an Ethernet cable so not wireless. That is against the rules.
For this to be a problem OFCOM will have to enforce an outdated and unnecessary rule against mobile operators, and if they do that it means no more voicemail or call diversion for any of their numbers. They can try and pick on us, but we are not the ones allocated the numbers, and it would be treating us unfairly if they do not sort the other operators first.
Indeed, if an exception was made for call diversion I would say the mobile operator is just doing that, diverting to sip:...whatever and that is therefore as valid as any other call diversion they do.
What is needed is for OFCOM to formally abandon this unnecessary rule!
In the mean time, we do make clear to customers that 07 mobile numbers are intended for use with mobiles and recommend use with our SIP2SIM service - even if that is via our customer's PABX. So we are playing our part in trying to fit in with these rules anyway, even though we don't have to.