Q: how to active my new iphone in Pakistan

Did you already follow the steps mentioned in this article?

Get help activating your iPhone

There are several wireless carriers who support iPhone models, in Pakistan;

as listed among other regional country locations in this Apple support article:

•Wireless carrier support and features for iPhone in the Middle East - Apple Support

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For other sales, service, support, there were some authorized independent

service and sales businesses listed by product in Pakistan, as shown in

one of the harder to find Apple Locate by country pages...

•Locate Apple

https://locate.apple.com/country

Hopefully this information may be of help in resolving the issue.

Good luck in this matter!