[uknof] Recommendations for VOIP provider in the UK

[Nigel Titley]

Does anyone have recommendations for helpful and reliable VOIP services 
providers in the UK. We're currently on a Gradwell hosted PABX solution 
but it's been getting more and more unreliable and we are now starting 
to get customer complaints: queued calls are being dropped before the 
phones ring, phones unregister randomly and I get emails telling me  
phones have unregistered when they haven't, I can't block incoming SIP 
hack attempts because Gradwell can't guarantee what IP address incoming 
calls will come from, they don't do IPv6 etc

Looking for a very basic PABX system: 8 or so extensions, incoming call 
queuing, voicemail. Advice gratefully received.

Nigel