Ok..I know this is late but it should still help someone. I finally got my 2125 to connect via bluetooth to activesynce after many frustrating attempts. It has to be noted that I am using the Widcomm stack that came with my Thinkpad T60P, that might be the source of much frustration, anyway....
I think the main issue was that the widcomm stack identified the activesync service as the com5 port and you can't change it....and...it seems that you can't select com 5 as the serial port on your phone, only choices are 6 through 7. So, delete the activesync service in the widcomm configuration page. Delete your pairing with your computer from the phone.
I then went into the widcomm bluetooth pairing setup and selected "add bluetooth device". The phone didn't connect but a popup stated that it created a new activesync service with com port 8 (don't know why it chose 8) so I was encouraged. It didn't actually create any icons or anything so I then initiated a pairing from the phone and things started to work. It mad the connection then then asked me what service I wanted to use, it had serial port (**THIS DOES NOT WORK***) and handsfree as the options. I was looking for activesync (***THIS IS THE KEY***) so I selected the menu in the bottom right hand corner and hit refresh and then lookee there, activesync showed up. I selected activesync and and it connected. I went on to initiate the activsync via bluetooth option from the phone and everything worked smoothly.
A couple notes:
1) I did make sure that in the activesync connection options, it shows com 8 as the port
2) The strange thing is that when I look on my phones com ports...it shows com7 as the one connected to the computer. I don't know if this is coincidence but com port 7 shows up as the serial port on the "Client applications " tab of the widcomm bluetooth options/configuration. Bluetooth on these phone make no sense to me...
3) I retried deleting the pairing, then setting things back up again and it still worked thus convincing me that the main issue was the com port (5) assigned in the default widcomm stack...delete this, force it to create a new one when you pair your phone (don't create your own) and then things should work.
4) I also tried deleting all pairings and the widcomm activesync service to recreate what I had done...man...what a pain in the butt. It wouldn't work the same way so this is a warning... The pairing would startup, the popup came up stating that activesync was connected to com 8 BUT when I wanted to select the service, it only had serial port and handsfree *@#$@#@$#@#$. I hit refresh and nothing @#$#@#@$#@. I did this multiple times and it I finally got the activesync service to show up again...** I don't really know why or how ** HAVE I SAID I HATE ACTIVESYNC AND BLUETOOTH TOGETHER
****What I think worked in getting the activesync service to showup as an option was.....I initiated a pairing from the computer and selected the activesync service, I then went into edit the pairing through the phone, when it came to select the service again, for some reason activesync was there, I selected and everything works again. I AM NOT TOUCHING THESE SETTINGS AGAIN. You will just have to fiddle with multiple options, probably took me 20-25 minutes until it finally worked.
Good luck to all and I hope this helps someone.