Register OK but no sound?
 

It's a bit intriguing, the set up works fine in my office using the normal Internet, back at my hotel it register fine, but then when you make a call there is no sound heard, where should I investigate? Give me a clue

Most likely, the hotel has firewall or router issues that are blocking a needed port. Both SIP and RTP ports must traverse the hotel's firewall and router.

Ron

ports
 

But if it register, the 5060 should be OK? then how could they block rtp ports, quite a range to block?

By blocking all ports by default and only opening ports to connections initiated from inside the firewall - e.g. 5600, opened by the outgoing register.

It does not make sense that they should open specifically 5060 while blocking the rest, as far as I know that is a SIP port and by consciously opening it they are implicitly saying that SIP is welcome and then to go and block all the other RTP ports doesn't seem to make any sense to me.

They don't open the port. You open it, by registering. You need to read up on NAT, SPI gateways, and that sort of stuff.