[Freeswitch-users] External/internal profile

Hello Today I can not understand the internal and external profiles. I've used other times asterisk setup and both the carriers and customers share the same ports and same ips. I do not quite understand because FreeSWITCH must use different ports (do not know if you can configure the same ports. In all the how-to I've seen that change the profiles and use different ports). Could anyone guide me for this?. If for example I have a server with two public IPs, you could configure each profile with an ip and both with the same ports (5060 and 5061)?. Perhaps it is an obvious question, but do not quite understand the issue of profiling, I have doubts. Thank you very much. Best regards.