Mobile number portability (MNP) or mobile number portability is a service by which consumers are allowed to change service provider companies without changing their mobile numbers. The service was implemented in India on 20 January 2011. Prior to this, this service was first started in the state of Haryana at a small level in India.
It is not possible to know that your mobile number is saved in the mobile, but you can find it partially. For this, make a broadcast list of the numbers you have saved in your mobile phone book by going to WhatsApp.
Send a message in that broadcast list and after sending it, check to whom that message has been delivered. The feature of this broadcast list is that your message will be delivered only to those numbers that have your phone number saved.
Those whose phones do not have your number saved will not receive that message, you will get to know which mobiles have your number saved and which ones do not.
The limitation of this experiment is that it can be done only on phones with WhatsApp numbers. Other phone numbers which do not have WhatsApp cannot be checked by this.