[Asterisk-Users] Any work around for ISPs that block port 5060 and 69

[Joel Jn-Francois]

I have a several friends registered on my asterisk box that are experience 
problems with their ISP blocking SIP default ports 5060 and tftp port 
69.  Is there any way around this problem or are they forever doomed to 
VOIP since their ISP is pretty much the only ISP company on that 
island.  So far I was able to have them change their default SIP port to 
6070 and any packets coming in on that port on my asterisk box I would 
redirect to port 5060.  That seem to be working fine, expect that they can 
make calls but cannot receive calls.  I think part of the problem might be 
that when asterisk tries to initiate a call to their sip phone it tries on 
port 5060 instead of 6070 even though I have specified in the sip.conf that 
their port is 6070.  Has anyone else encountered this problem and was able 
to resolve it?  My other option is to change my asterisk box to work 
completely on a different port, but I am reluctant to do so since the 
majority of registered users for now do not have an issue with port 5060 
being blocked by their ISP.

Thanks for your help.

Joel