07399 is a new prefix, which virgin calls are barred at the moment.
07399 is a new prefix recently added BUT virgin have not added it to its computers as of 23/12/2015. I was told this by a technical bod at virgin and he told me it will be working early 2016. how early who knows.
Re: 07399 is a new prefix, which virgin calls are barred at the moment.
On the assumption that the "big 3" operators can all call this prefix, then this is one of many reasons (no offence to Virgin intended) why I will never use an MVNO for my main mobile service. Only having an indirect support path to the actual network operator is not my idea of fun when anything goes wrong.
I suppose it's the same theory as applies to BT Openreach/ISP reseller, thinking about it.