We have had a couple of instances where clients have been unable to make outbound calls with their PrepayGEO VoIP (SIP) accounts using the Groundwire app. In all cases the client could receive inbound calls, but could not make outbound!
This is due to a proxy configuration issue which occurs on some internet broadband/DSL routers. This can be resolved by following the below instructions.
1.Click on Settings, click on Enabled Account, then click on Advanced Settings.
2. Click on NAT Traversal, then scroll down and click on Outbound Proxy. Enable Outbound Proxy and input sip.open-telecom.co.uk into the Host section. Once you have done this, click Done and Save all changes.