There's a CDMA network operating in many of the major cities across Pakistan that has a fairly interesting prepaid package offering most international landline calls for between 1.1c and 1.7c per min, and international mobiles at 5.7c/min. There is a monthly fee of about €1.70.
See:
http://www.gocdma.com.pk/low/res_prepaid.php
There is another independant US service offering interesting termination possibilities onto this specific network. For $24.95 a month you can chose a fixed number in USA, UK or France which will be diverted to your Pakistani number on this network. I am not sure if this is just a temporary arrangement as same-network calls are free at the moment on the Pakistani carrier.
See:
http://www.superphonewireless.com/