I think we should study what exactly the ISP or the University is doing when it is trying to block SIP. Is it only inbound 5060 being blocked, or outbound too? Doesn't the NAT port-shuffle tend to obfuscate the ports used anyway on the WAN side? Can't end users change their ATAs and IP phones from 5060 on the SIP port to something else? It would seem best to know how exactly universities and some ridiculous ISPs are blocking SIP before we can come up with effective workarounds.
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