Sipgate servers i think are in Germany, vonage in the US and Voipfone in the UK.
A lot of our customers use Voipfone, it is a no brainer here really as UK based servers mean latency from our core router is in the lower single figure milliseconds and does not have to traverse continents.
For business use they have all the toys you need and they are pick and mix , use what you need etc..
Our own offices have been entirely Voipfone for many years , wouldn't ever go back to BT, none of our customers have wanted to go back either.
It is a breath of fresh air
. Plus they also benefit more than most as unlike the majority of Broadband services, ours has no need for a BT line or line rental.
Bill Lewis - MD
Fixed wireless ISP - ISPA/CISAS/RIPE member