We have 5 voip accounts to the same provider, all with different numbers assigned to. If we register them they're ok but after a few minutes, the connection drops, if we use only 1, it stays online. If we use the same accounts from our voip snom-320 directly, it works (1 per phone). We can not get our VOIP provider to work with DID because their system requires 3 logon fields (endpoint, userid and password). We can add DIDs on the provider endpoint, but then the supplied called number is always the main account number, never the DID. they could fix it by using authentication by IPaddress, but that's not supported by 3cx,I think.