Important bit of info by Tee Em on Karachi Met Blog 

PTCL has quietly activated answering service on its phone lines. I called various places in Karachi today for official purposes and ended up at listening to the answering service prompt.

If your home or office phone number gets a bill of Rs 1,400 per month or more, your line has been crowned with this unsolicited ‘facility’. Of course it is not necessary for PTCL to tell you how to retrieve the messages that your dear callers have deposited in your mailbox by paying Rs 2.01 each time your phone number was engaged and they were presented with an prompt in English language!