The Gigaset pro Interoperability Program is designed to test Gigaset pro PBXs when connected to ITSP (Service Provider) SIP Trunks. If you are missing local Providers you can contact the local Technical Sales Representative in your country.

SIP Trunking for Gigaset PBX Systems:

Country	ITSP Testing
France	Link to tested providers
Germany	Link to tested providers
Greece	Link to tested providers
Netherlands	Link to tested providers
Switzerland	Link to tested providers
United Kingdom	Link to tested providers