There are a lot of good reasons to opt for a VoIP service instead of a traditional circuit-switched phone service. VoIP plans can save you money and provide you with features plain old telephone services can't offer. Unfortunately, there's also at least one reason you may want to consider sticking with your old phone service, at least for now. That reason is line number portability, otherwise known as LNP. The FCC isn't currently requiring VoIP service providers to comply with the number portability requirements they've placed on cell phone carriers and standard telephone service providers. This means that if you decide to leave your VoIP service, you may find yourself parting with your phone numbers as well. Large VoIP providers such as Vonage and are generally more capable of handling LNP, but even these services seem to have restrictions on porting numbers. Smaller VoIP providers often lack the infrastructure and business processes for porting numbers. If you're thinking of moving to a VoIP service and value your phone number, ask your prospective VoIP service how it handles LNP and if you'll be able to take your number with you should you decide to leave the service in the future.