After the firm later went in to liquidation, one of it's previous members (a bit of a technical whiz) put his mind to inventing a system for the military where any mobile phone call, anywhere, could be monitored and located using the technology available in GPS satellite tracking. Boastful Taliban and Al-Qaeda franchisees who previously thought themselves untouchable in remote desert areas, suddenly found themselves being targeted and killed.
I'm not sure any of that is true.
Most of the mobile location technology was driven by the E911 directive which was to locate mobile phone users in the US rather than Afghanistan, so they knew where you were when you call 911. It doesn't use GPS tracking as GPS is read only - and most phones don't have GPS receivers in them. Most of it is done by triangulating the signal either from cell towers in dense areas or from overhead eg Nimrods, drones etc.
As for knowing who is calling who, all the MNOs in Afghanistan have had all their calls tapped by the NSA and GCHQ for years, so they know who is calling who when and then just locate the SSID from the triangulation.
The locals have got wise to this though and for a while forced the MNOs there to switch off their networks at night, so they could move around undetected. (They were not smart enough to just take the battery out their phone, then move around, blow something up, go home and then put the battery back in).
Also, if you meant Granger Telecom, their staff were killed in Chechnya rather than Afghanistan: http://news.bbc.co.uk/1/hi/231570.stm