How to use cell phone numbers portability?

Mobile number portability is referred to simply as WNP or WLNP (Wireless LNP). The United States is one of the few countries in the world that offers full number portability transfers between both fixed lines and mobile phone lines, because mobile and fixed-line numbers are mixed in the same area codes and are billed identically for the calling party, the mobile user usually pays for incoming calls. For getting the mobile portability service you have to contact your prospective new carrier, who will start the porting process. The new carrier will first confirm the your  identity and then make a porting request of the old carrier. When you go to your new carrier to port a number, you should bring along a recent bill, which will have your correct name and address as it appears in the carrier’s database. This should aid in making the porting process go smoothly. Once a valid porting request has been made, the old carrier cannot refuse to port a number. For a wireless-to-wireless transfer, the porting process should take approximately two and a half-hours, from the time the porting request is made of the old carrier. During this time, the number is being ported from the old carrier to the new carrier, there may be a period of "mixed service" when 911 services are affected. If you call 911 during this period, the call should go through. However, the 911 operator may not be able to call you back if the call gets disconnected.