I work in a famous Mobile operator of Pakistan so many people ask me, how to find or trace the location of Mobile number in Pakistan? To understand this first we should know how mobile technology work. Mobile companies provide coverage by dividing the area into smaller areas called as Cells or sectors. Each cell is given wireless coverage by 3-6 antennas fixed in specific directions, mounted on a tower. Usually tower is located in the center of the cell. When mobile is powered on, it continuously remains in communication with a specific antenna. Mobile companies can check at anytime that a specific mobile number is in which cell and to be more specific on which antenna to know more accurate position. For example DHA is a cell and a specific antenna on a tower is giving wireless coverage to Phase-1 of DHA.
Friend in a Mobile company
Few technical engineers of a mobile company have access to the monitoring system to find location of a number or mobile (IMEI). However your friend or relative working in a mobile company can do this by using his contacts.
Law enforcing or Intelligence agencies
Secret agencies of Pakistan like ISI and MI have access to the system to trace location of a specific mobile number. Police can also do this but to limited extend. If you have some contact there you can use it.