[Stu]

I was looking at a service called Voxalot. It is from the same folks who gave you sipbroker.

Voxalot is a personal voip consolidator. You can register various sip based accounts with them, and then connect with your own analog telephone adapter, etc. What is more interesting is that you can get say a free sipgate uk geographic number and connect it directly to a voip carrier that has a cheap route to your prepaid sim in another country. If that route collapses, you can go to plan b while still keeping the same number.

They also have a web based callback system which also has a mobile friendly version of the page.

Stu