Sorry all my pyromaniac friends but this is a grumbling about comlinks, not flamethrowers (which I admit rock).
A good friend of mine introduced me to the concept of "sanity checks" as he calls them. When you make a Shadowrun character pass it along to someone and let them go over your stats and gear to make sure you haven't done something insane, or forgot something simple.
Like a burner comlink, and a dummy comlink.
Coming in at 100 nuyen the disposable comlink, or a simple metalink comlink is a runner's best friend. In ye days of old a SIN was carried on a credstick like device. Want to use the bus, slot your SIN. Want to get a burger at McHoughs (you poor bastard), slot your SIN. Since 4th edition the Matrix went wireless and as such a SIN, both real and fake, became a digital item. In polite, or rather legal society you have to keep your comlink in public mode broadcasting your SIN. This lets people know you're a legitimate citizen, not one of those scummy SINless sorts. The problem with running your comlink in public mode is that you open yourself up to all the wannabe deckers out there.
So the dummy comlink comes into play here. You slap a few sims on there, maybe a music list, some contacts you've picked out of the directory and your fake SIN. Switch it on broadcast and you look like a real person. Sure its easy to hack into due to its crappy firewall, but that's the point. You're not using it anyway, in 4th edition at least you could even set a script on it to have it reboot itself after a period of time.
Then there's the burner comlink. You have taken all the time making connections in the shadows, you've protected your comlink the best you can and you keep it hidden. Its one of the most essential pieces of gear you can have on your list. You go on a job and you meet Mr. Johnson, or worse yet some random yahoo you have to con during the course of a job. They need to get in contact with you, but you don't want them being able to track you down once the job is done. So you spend 100 nuyen at the local stuffer shack and buy yourself a disposable comlink. Pull the tab and its active for a week, works just like the real thing, and you can give out the LTG to whoever you need. Once its served its use, you just toss it away, no fuss, no muss. At 100 nuyen a pop, there's no reason not to have two or three on you at all times ready to be used at a moment's notice.
So, in closing, use your comlinks wisely. Use a burner to deal with "legit" people, use a dummy comlink to look like a legit person and always, always, keep your real comlink safe.