I had previously determined the format for sending text to the head unit but I had noticed despite been able to activate the Uconnect and connect to it via bluetooth I noticed with it sitting on the bench It was not sending the text to for the headunit.
I figured there must be some response from the headunit once it recived the request to switch to phone mode.

I took log from the car for a phone call and loctated the "Connect" text 3f5# and searched back in the log for the "switch to phone mode" 2d0#82 and played that to the Uconnect module and next time I made a call the text was been sent.

pruning the log down by 1/2 and replaying the log untill I was down to a only a few lines and then took a couple of stabs in the dark and nailed it with

293#410240F202000000

I dont know the format but that data string gets the job done :)

It appears that the Uconnect module doesnt care when the string is sent but at least I can now look out for it and use it as a check to make sure I have succesfully connected to the headunit.