I have to admit, it took me a while to understand the voice over IP trend (think Skype, Vonage, or iChat AV for that matter), mainly because it has never actually worked for me. Turns out, that was all my fault.
Constant disconnections have always been frequent. I could rarely sustain a conversation over 5 or 10 minutes, whether it was computer to computer, or computer to phone. I often wondered how anyone could make a case for using VOIP on a frequent basis, and assumed the grass was somehow greener.
My current setup sees my cable modem piping into a wireless router, which I’ve used variably as a wireless or wired hub. I bought it before I was thoroughly versed in the world of Apple so it’s not an Airport, it’s made by SMC. Which means manual configuration.
Now, I’m a bit of a networking geek; I can tell you the difference between NAT and a MAC address, when you’d use DHCP or manually configure an IP, and I can even explain the difference between the TCP part and the IP part.
So, I assumed I had set everything up to work properly (and low bandwidth applications like email and the web worked fine) and it was just my local service provider having issues, or my wireless B-generation router just wasn’t capable of the speeds needed to carry voice and video. Streaming video has always been a problem too, seemingly lending support to my theory. For years I’ve thought this.
A few things came together that pointed to a solution. 1) I bought an iMac that has a built-in iSight. 2) after SXSW Cindy Li hosted Veerle and Geert in Washington. 3) a stroke of inspiration led to 60” TV iSight chats that kept crapping out on us. That’s when Cindy mentioned that iChat AV had a few specific ports that she had to open manually on her router. Hmm.
A bit more research, a bit of plowing through iChat error logs, and it quickly became clear that it was my router’s NAT (Network Address Translation) that was causing the problem. After a few minutes of any chat, the expected delivery address shifted and the connection dropped. Whether I was plugged in with an ethernet cable, or connecting over the wireless, I had the same problem.
I’m going to gloss over a bunch of configuration here, and skip why manually overriding ports doesn’t work very well when your systems use DHCP. But I will say that in theory NAT seems nice and secure, as any computers within a network appear to come from one single IP address: the router’s. So, for the most part, any hacking from the outside could only ever get as far as the router, leaving the computers within the LAN safe enough.
Point being, it’s hard to think about turning that off since it’s clearly a good thing. So I never tried. But after a bit of time on the phone with the local Apple retailer, I decided to bypass the router completely and plug the iMac directly into my cable modem.
And like that, the problem went away. I managed to maintain constant connections over a series of calls yesterday totaling almost two hours of talk time. So the problem was most definitely NAT-induced, and after eliminating that as a factor, I can now do remarkably clear and reliable VOIP sessions.
Now the question is, do I simply turn off NAT, or buy an Airport/Airport Express and expect it to deal with all this gracefully and securely? That’s what I’m not quite sure about yet. Anyone?