I use tesco internet phone for my SME
It proved very useful as I travel a lot.
Apparently this is because freshtel are in financial difficulty
http://www.computerworld.com.au/article/336985/freshtel_forecasts_1_25m_loss/
However it leaves me with a dilemma, I have business stationery printed with the tesco number all over it, and a nice shiny handset locked to tesco which will become a nice paperweight soon.
No new yet as to if they will allow you to transfer the number elsewhere. If they wont I will have to try and lodge a complaint with ofcom.
If el-reg can dig up any more information it would be appreciated, it seems tesco are not interested in helping their customers.
The service was excellent as well, I trialled it for quite a while before deciding to commit to using it for business use.