The iPhone comes with nice iPhone earphones, but they're not ear-blocking like my old Shure E3cs or my Ultimate Ears. This makes hearing TV dialog of video on the subway significantly harder, and the UEs don't fit the iPhone's headset jack. Now, of course, there are many 3rd-party headsets with iPhone-style stereo + microphone connectors, but they were rare (nonexistent?) when I got the UEs for my birthday. Ouch!

I used the UEs with the Treo 650, using a $5 Radio Shack 2.5mm-3.5mm converter to connect the 3.5mm earphone plug with the Treo's 2.5mm phone jack. Rather than un-wedge the UEs, plug in a standard single-ear-plus-microphone voice headset, make a phone call, then remove the phone headset in favor of the UEs, I just moved the connector from my iPod (for music) to my Treo with the adaptor (for video or voice). Now I wear one headset and it does everything without switching. This is good. It's also nice that I can hit the mic bump on the cord to pause the music/video playback in favor of answering the cellphone, and when the call ends playback resumes.

It will be good when I replace these earphones with a louder/noise-blocking set, but in the meantime I'm appreciating the convenience, and using the mic bump to pause video playback whenever there's loud subway noise or glare prevents me from seeing the screen.