Last night, I just heard on a TV ad (but, I did not give a look at it!) that a SIM card of Afghan Wireless Communication Company (AWCC), a GSM provider in Afghanistan, charges only 2 afghanis per min while making a call with another AWCC's SIM card, and 4 afghanis with all others. The normal charges for making a call in Afghanistan, almost common for all GSM providers, is 5 afghanis per min.
I am pretty sure this is not the good way of marketing. AWCC is willing to build an advantage for itself, by lowering the prices, but why does it also, by itself, put some limits on this advantage?! It is like that, in a marathon, while nobody has any shoes to run, but you have one, and this is a great advantage for you, but you're putting a nail in your shoes!