I bought iPhone 7 plus from your shop.... I want to use the phone in India, when we using Indian Carrier...Phone shows that invalid sim., please contact your carrier. as the Phone is under carrier lock.

You can't use locked phones in other countries unless your phone carrier would be willing to unlocked your phone. You should buy phone that's already unlocked, then you can insert & use the SIM card from any country you visit. Having unlocked phone is very convenient when you travel international.

You have to purchase another sim card that works in India