GPS+GSM Module Suggestions

Hi All,
I am planning to use sierra wireless's HL6528 GPS+GSM module for the development of GPS Tracker.
Could any one here share their experience about the module or the remark on the sierra wireless products?
My requirements are very stringent so that the GPS should track the location in the indoor scenario.
Its should be very reliable and have good performance. I agree that this could be achieved with overall design and component selection but, I would like to know w.r.t the GSM/GPS module which play key role in the application considering other parameters are taken care.
Please share your thoughts help me in selecting a good module.
Looking forward to hear from you

Regards
Anand M