Firstly - awesome, you probably are one step ahead 
Second - AMAZING! That looks great. Looking at the U201 docs though, there appear to be about a million different mechanisms the chip can be used to get location info (i.e. GLONASS - and variations - GSM location, combinations of these etc) and some of these will require a valid GSM connection to function while, presumably, GLONASS-only options will not.
This is why I wanted to look into sending custom AT commands to the chip to configure the location params needed.
But if you're already there great, I'll use that - or maybe expand it to take in params to configure which combination of sensors to use for location info?
Thanks!