In his latest blog post Thomas Howe, the master of mashup, was so kind to explain again what mashup means:
A mashup is an application that uses
1) modern Web integration technologies
2) to take content or services from two independent sources
3) to solve a unique or niche problem.
The second element of mashups is that they take content or services from more than one independent source. This is where the “mashup” word comes from. Mashups take things that might not go together, and puts them together in a valuable way. The classic mashup is the Chicago Crime Map, that took data from the Chicago Police Department and plotted it on Google Maps, so that you could see where the burglaries happened.
The "Sipgate API" is provided free of charge and can be used for mashups with every Sipgate account. Up to date the fax function of Sipgate can be used only with the German service.
To make integration easy, Sipgate publishes also the source code of the Firefox extension "Sipgate FFX" as well as several Perl examples and a KDE panel application under a GPL 2 license. Further more .NET developers will find with "sipgate API .NET SDK" a comfortable library to use the "Sipgate API" services easily. Over a mailing list developers can also exchange experiences and tips.
You will find all information about the interface and the exemplar applications including detailed documentations under www.sipgate.co.uk/api.