[Freeswitch-users] external inbound sip call questions

[Josh]

A few questions to all knowledgeable heads out there: Everything I read 
so far about how to set up and configure my FS external sip profile 
tells me that I need to have IP address/interface and port (default 
being 5080) to bind to in order to receive inbound calls via the 
external sip profile.

Is that really the case? Is this the only way I could receive such calls?

The reason I am asking is this: my Internet-facing interface cannot 
receive calls (or any connections from outside) unless it initiates 
these connection first, simply because my ISP is blocking "server" 
connections (i.e. connections initiated from outside, destined to my IP 
address/interface). If my Internet-facing machine initiates the 
connection first (therefore punching a "hole" through the ISPs 
firewall), then that's allowed - no restrictions of any sort are applied 
by my ISP.

So, I guess what I am asking is this: Is it possible to configure my 
external sip profile in FS in such a way so that it does not listen to a 
particular interface:port in order to receive external sip calls, but to 
use the control channel/connection established to my external SIP 
provider (on sip provider's IP address and port 5060) in order to find 
out which ports to use and initiate rtp connections on my machine, 
instead of waiting for such connections on a specific port? As I already 
pointed out above - such connections initiated from outside will be 
blocked by my ISP, but if these are started from my machine they will be 
allowed, no problem.

Hope I am making myself clear with this. Many thanks!