Phone to Audio out.
I have the 720. It use to play the phone conversations out to the FM transmitter and the/or the Audio out out jack. That stopped a few weeks ago after a upgrade. I contacted TomTom support.
The first lady that I talked to was no more effective than a voice robot, merrily typing away in the background, telling me to reload, reboot, and reset to factory defaults, and if that didn't work, call back and they would instruct me on how to format the unit.
Obviously she was working off the same idiot card that is used by some overseas tech support groups.
I hung up, had a cup of tea, and called back. The tech I got this time was a much brighter light bulb. He advised me that there was a trouble with an application and that TomTom was aware of the problem. He told me that there will be a patch issued on 3April08 to correct this problem. He also mentioned to actually check for the patch on 5April08, since his experience was that sometimes promise dates don't always match up to release dates. Wow, a tech that tells the truth! I'll respect a company that tells the truth any day.
As a CYOA, you may wish to back up your Voice Recognition files before applying the patch, just in case.......
Cheers,
Eric