I reported once here about not being able to call the car (and no link app updates) I had to place a call from the car and the problem cleared. Never saw this problem but once and I am using Iphone 4s bluetooth. There was no change in onstar minutes except for the 1 min call.
Where I park is by the house and its 50/50 if WiFi or cell is use for the internet ( just adding this to the mix) latest Apple official IOS ,Sprint
2012 RED Volt VIN:#C-8860 - Premium Leather Seats Jet Black with Dark Trim, Rear Camera & Park Assist, Nav
09/29/2011 Ordered -- 11/15/2011 took it home