No Facetime On My iPhone 4
PK-UFONE is a Pakistani carrier. 

Pakistan is not listed as a country that doesn't support FaceTime, but some have similar problems and can't use FaceTime:


  (Sep 8, 2012) i do not have facetime option on my iphone 4 with operating system IOS
  5.1.1 please help me.


In another post a user states:


  (Aug 14, 2012) I have bought my iphone 4s from Apple Store in Birmingham,UK.I am now
  in Pakistan and connot use Facetime as the verification phone number
  displayed is that of UK.


Others successfully activated FaceTime, but activated it abroad:


  (Feb 3, 2011)
  I am not sure if it will 'activate' on a carrier in Pak. Can only
  share my experience that I hd similar situation but I activated it
  before coming to Pak and FT worked just fine on Ufone carrier.


I'd recommend that you contact PK-UFONE. Maybe you simply need a different plan to activate FaceTime.

I doubt this will help, but you can also check this Apple article for troubleshooting: iOS: Troubleshooting FaceTime.

There is a similar question related to an iPod here.