Forwarding to sipgate not working

Hi I’m desperately trying to forward our flynumber to a service called sipgate. Haven’t found any topics here so I thought if anyone might have an idea.

http://www.live.sipgate.co.uk/team (this is a standard cloud based pbx using standard sip protocols)
I tried all sorts of configs but I either get a “Decline” or “Proxy Authentication Required”… any suggestions?

Hi

This looks to be a restriction on their side, can you ask them if your SIP URI is open to outside DID providers?

Thanks