I've installed centos 7 on a cloud server and Issabel (asterix 16) onto it. I have done the configuration required. The internals can call each other, we can talk. I also added sip trunk. However, the internal local doesn't make global or gsm call. When I make call it shows 'wrong number' error. I've tried two different sip trunks. In the first one, the allocated number starts with +44 and in the other it starts with +90. I haven't installed the sip trunks to the system at the same time. What is it causes the problem?