Redline Software (the company I slave for) has taken the plunge and decided to use Asterisk and a SIP provider and say goodbye to BT forever, well almost were still going to have one analog line for emergency's.
We have spent the last couple of weeks figuring out what makes Asterisk tick and selecting a SIP provider and have decided to use VOIPtalk and Swissvoice IP10's handsets. We will make use of voicemail, huntgroups and call forwarding. VOIP talk charge £9.99 for setting up an inbound 0845 number and there call charges for the UK are low 1.4 p a minute.
We were quoted £3500 for an Alchemy IP Office solution with IP handset and ISDN2 termination which I thought was pretty reasonable. It will cost us £2000 for handsets and a server to run Asterisk on!