Treo's are a pain. I've got a 700wx for work. Even if it did sync properly I'd still have to manually flip the bluetooth between this phone and my personal phone which is an LG VX9900.
For me, it's simple... The Treo is my work phone and when I get in my personal car, it is quiet time and folks can just deal with Voice Mail for a bit. Anyone who I might WANT to talk to has my other number and that works great.
For you, perhaps you should download the latest firmware/software flash updates from your carrier, or from
www.palmone.com
Updates are posted for download regularly to address compatibility issues like this.