PC-to-PC and PC-to-Phone SIP Providers
SIP (Session Initiation Protocol) is a widely used communication signalling protocol used for real time voice and video communication over the internet.
SIP Service Providers
SIP service providers allow you to make worldwide calls using Express Talk. Most companies offer free PC-to-PC calls because they make their money from providing PC-to-Phone connection services. That type of gateway service allows calls to and from traditional telephone line will come at a fee, but will tend to be cheaper than the rates from the phone company.
Call Centric offers good service. They are based in the United States and are video phone capable.
inPhonex offers free PC to PC SIP service as well as providing real numbers for residents of the USA, Canada, and the United Kingdom.
VoIPtalk is a large European provider based in the United Kingdom. If you are in the UK you may want to try their service.
Sipgate offer a basic service that lets you ring any land-line number you like, but it won’t let you use on-hold or transferring functionality.
Note: Many providers a download of their own branded version of Express Talk or other softphone. We recommend you use the standard Express Talk to avoid being locked to a single provider. That way you will be free to use different providers for different lines and can more easily change services. If you’ve already downloaded Express Talk there is no need to download a softphone when signing up with a SIP service.