074 040 Mobile Lycamobile UK Mobile WiFi FW7 WiFi Services Lycamobile UK
These numbers are indeed routed differently. If you call them your call is actually dialling into a server which is linked with other worldwide servers owned by the network you are calling. Thus Lycamobile and truphone can offer cheap rates in selected countries they are based in. So in uk with its server on o2. You actually physically roam on them. a landline call is sent through their servers and actually looks like is routed via some sort of voip so will explain why it shows unavailable on my caller display also why talktalk rates it as a wi fi number that the call routes to a server rather than mobile company
I suspect they've just got an 074 number allocation from Ofcom as a VoIP provider, setup an SS7 to SIP gateway (they may not even need this with ENUM), shoved the traffic through an Asterisk box to route outbound via whatever penny pinching company is cheapest for the current hour, then routed the mobile part to their roaming partners via the HLR.
Network Lycamobile UK Limted
Use Mobile services
Change date 08-2009
it is possible to list every exception in the small print