EchoLink
(this is a re-write of my original post to tidy it up)
I signed up to EchoLink today and installed EchoMac, a Mac version of the software. I have yet to play with this other than making calls to the *ECHOTEST* conference - a self-test facility like you get in Skype.
Getting the software to communicate was a bit of a fiddle, through no fault of the software or EchoLink. First off, the home router needs to be able to pass UDP ports 5198 and 5199 in both directions to the Mac, and port 5200 TCP outgoing. The information is here http://www.echolink.org/firewall_solutions.htm. By default everything incoming is off other than a few rules that I have for the web servers. So I had to enable this. The Sky router I have can be a pain here because more often than not, pressing Apply to save firewall rules gives a 'not found' error and it seems to want several goes before it works. No idea why that should be, surely the script is either there or not, not there sometimes! Anyway, I got the rules in. Note on the Sky router you need to first define a Service for those UDP ports, then select that service for the firewall rule.
But it still did not connect. Over to the Mac firewall which was already switched on. Not sure I did this, maybe the latest software update sets it by default. Anyway, here I needed to select EchoMac and allow it to accept incoming connections. It seems I also needed to reload EchoMac to make this work, so I guess the firewall only permits an application when it loads, not if it is already loaded, which makes sense.
There are still connection issues though. I can connect more reliably if I chose the Sky router as the wifi hub. Every test so far when connected to my main hub results in no connection for EchoHam, but switching to the Sky router wifi and it usually works. I say usually, because if I connect to the Sky box and load EchoHam it works, but then if I unload EchoHam, switch to the other wifi hub and reload EchoHam it still works. But not always! I'm sure this is a fault of my own security because I can get it to connect, just not always first time.