Hi, i really need your help!

I´m sharing my internet with my neighbour (next door). He is connecting his latptop by wifi using my ubiquiti antenna, this is working fine, i have the ubiquiti antenna connected to a RB750 Mikrotik with hotspot.
He has also a PC with no wifi and he wanted to have landline also, so we bought an ubiquiti AirRouter and also a Cisco ATA SPA112, we have setup the router as Bridge and pc is connected by wire to the router, that is working perfect, mikrotik is giving by dhcp IP to both computer and ATA.

The problem is that the ATA is not working, we have setup the ATA mac on the IP Bindings and also the sip servers are on the walled garden, but still not working... and already took out from mikrotik firewall.

I took the sata to my house, connected straight to the internet provider router and works fantastic....

So i really dont know what to check or modify or whatever... Any ideas why is not working trought the mikrotik?

Please post your: Ip config, Nat config, hotspot config, route and dns config.