We just install and first time a Yeastar S100 in our office in Cairo.
In Paris, we have Sonus SBC 1000 , both office are connected by VPN IPSEC connexion.
I would like that users from Paris can call the users in Cairo by extensions and Vis-Versa
the second needed implement the least cost between two sites by reduce the call cost.
Can you please supply me by any documentation or send a step by step.