Sipgate Basic are the only ITSP that I am aware of that offer free geo numbers (UK) and only charge on a per-minute basis.
Calls with them cost 1.18p/min to a UK landline and 9.90p/min to a UK mobile.
Net Telco offer free geo numbers (UK) but I don't think they offer outbound calling and there are conditions that you must adhere to.
Net Telco wrote:A FREE UK Number from Net-Telco is just that – a geograpic or non-geographic telephone number in an area code of your choice which is totally FREE OF CHARGE.
There are many benefits in having a FREE telephone number from Net-Telco, some of which are:
We simply provide free telephone numbers that you can forward to a landline or mobile number. All you have to pay for is the forwarding call cost and thats at our ultra low call rates.
- we give you a free UK telephone number from our drop down selection above;
- there are no setup costs;
- there are no annual costs;
- the only thing you pay for is the cost forwarding the call;
- all we ask is that the number does not go for a period of more than 28 days without being called and answered.
You can buy numbers if you want to select specific numbers or are wanting to forward to VOIP destinations, or are wanting to use our advances features (Call Announcement, Call Whisper, Voicemail, Fax2Email etc.).
I think you'd be better off making direct contact with a VoIP provider of your liking and ask them outright what your options are. Some VoIP providers heavily discount additional numbers when you have hundreds of them (let alone thousands)! Either way, be prepared to spend some £££.