While traveling in Pakistan which language should I communicate in?

The national language is Urdu . Each of the four provinces have regional languages which are Baluchi in Baluchistan, Pashtu in North West Frontier Province, Punjabi in Punjab and Sindhi in Sindh. But English is the official written language and a medium of communication in all offices. All signboards are in English and most people will be able to understand and talk to you in English.