Noise problems My Palm Treo 600 seems to have a lot on interference noise when I talk on it. My last one did the same thing. It gets worse around electronics

An old battery can sometimes be the cause of buzzing sounds, it grows louder when the battery runs lower, and when reception is poor.

If the battery is old, consider replacing it with a new one.

This is a common problem, the solution is actually called the "Treo Buzz Fix".

Earlier models of the Treo 600 had an unshielded cable that connects the battery to the main board. This cable causes loud buzzing and interference on the Treo.

If your treo is under warranty (unlikely probably...) then send it back to Palm for replacement.

If not, try the fix. The fix involves disassembling your Treo and wrapping aluminum foil around the offending cable. Here is a guide:
http://mytreo.net/treofaq/BuzzFix

And here is a forum on MyTreo with high resolution pictures of the process, to help you:

http://mytreo.net/forum/index.php/topic,54886.msg429525.html#msg429525

This is a somewhat dangerous procedure. It is possible to damage your treo if you aren't careful. Follow all instructions EXTREMELY carefully.

Good luck! And don't break your Treo!