andyha,
You will most likely have to call the OBi and go trough the AA to make another outgoing call, as I don't think installing the OBi App on a cell phone is a likely scenario. This example will accomplish a two stage call.
{(<**2>(5145551111|5145552222|x.5145553333)):aa($1)},{ph}
Note that this is actually a callback configuration. This setup offers you two call paths.
1) If you let the OBi pickup you can select Option#2 "make a new call".
2) hangup before the OBi picks up, it will call back the CID number you called from in the above config. You can setup multiple callback numbers.
You configure the behavior of the next step of the call depending how you want to setup your Primary line. Decide if you want SP1, SP2 or Trunk Group 1 as the Primary line. Depending on how you set this up you may or may not need to dial **1, or **2 in front of the Telephone number you are planning to call. You can also set up contacts in the speed dial. I'm certain that you have a few international numbers in mind. You can prefix those numbers in the speed dial with **2, if you want them going over GV.
Note: I can not say that my experience with OBi+Freephoneline has been rock solid. As I mentioned, I have not tried to find the reason why it happens. It may not be related to the OBi. It happens about once a month.
Tons of other fun things you can do with the OBi. Best way is to have a look at the Admin guide and read up on the forum. Have fun.
Edit: This example forces the callback over SP2 if you hangup before the OBi picks up.