how i can know what is my CID ?

[stam91]

And how to identify phone CID when buying the phone? (for example, K750i)

[k2bi]

And how to identify phone CID when buying the phone? (for example, K750i)

I dont think you can identify CID when you buy. Only way to use XS++, davinci etc. to check CID. Maybe you'll be lucky and shopkeeper lets you to check CID in shop. ^^
but I dont think so