Last year, One of my colleagues started using a very old model, simple Nokia phone (10~15 years old) which had been long forgotten, and the moment he inserted the SIM Card, he immediately got the message from PTA for device registration, and paying the taxes.
The tax amount was somewhere around 2500~3500 PKR, but was almost 5~7 times the current market price of that phone. Since he had to use it, so he paid the taxes and started using the device.
Sometimes, rules are very strange here.