Same happened to me. When I order iPhone 5s from abroad.
You will get NOC within 10-15 days sometime within 5 working days.
As for As IMEI number is concern. In place of IMEI number just mention: N/A (Its a bluetooth wireless headphone)
Also you can mention Mac address of bluetooth as every bluetooth devices consist of MAC address. If you do not know MAC address just mention what i told you above.
How to apply for NOC Follow this guide:
How To Get PTA NOC for Mobile Phone Import from Pakistan Telecommunication Authority