Editing Voice over IP (section)

===Number portability===
[[Local number portability]] (LNP) and [[mobile number portability]] (MNP) also impact VoIP business. Number portability is a service that allows a subscriber to select a new telephone carrier without requiring a new number to be issued. Typically, it is the responsibility of the former carrier to "map" the old number to the undisclosed number assigned by the new carrier. This is achieved by maintaining a database of numbers. A dialed number is initially received by the original carrier and quickly rerouted to the new carrier. Multiple porting references must be maintained even if the subscriber returns to the original carrier. The [[Federal Communications Commission]] (FCC) mandates carrier compliance with these consumer-protection stipulations. In November 2007, the FCC in the United States released an order extending number portability obligations to interconnected VoIP providers and carriers that support VoIP providers.<ref>{{cite web|url=http://www.fcc.gov/cgb/consumerfacts/numbport.html|title=Keeping your telephone number when you change your service provider|work=FCC|access-date=January 20, 2009|archive-date=December 12, 2009|archive-url=https://web.archive.org/web/20091212070455/http://www.fcc.gov/cgb/consumerfacts/numbport.html|url-status=dead}}</ref>

A voice call originating in the VoIP environment also faces [[least-cost routing]] (LCR) challenges to reach its destination if the number is routed to a mobile phone number on a traditional mobile carrier. LCR is based on checking the destination of each telephone call as it is made, and then sending the call via the network that will cost the customer the least. This rating is subject to some debate given the complexity of call routing created by number portability. With MNP in place, LCR providers can no longer rely on using the network root prefix to determine how to route a call. Instead, they must now determine the actual network of every number before routing the call.<ref>{{Cite web |date=2006-11-13 |title=TelePassport takes the sting out of MNP |url=https://www.itweb.co.za/content/5yONP7EKaWJqXWrb |access-date=2022-07-19 |website=ITWeb |language=en |url-status=live |archive-url= https://web.archive.org/web/20220719090004/https://www.itweb.co.za/content/5yONP7EKaWJqXWrb |archive-date=2022-07-19 }}</ref>

Therefore, VoIP solutions also need to handle MNP when routing a voice call. In countries without a central database, like the UK, it may be necessary to query the mobile network about which home network a mobile phone number belongs to. As the popularity of VoIP increases in the enterprise markets because of LCR options, VoIP needs to provide a certain level of reliability when handling calls.