VoIP did have a few disadvantages and problems associated with it, in comparison to traditional telephone service. Most of these have been solved/can be easily solved.

Just because the problems can be solved doesn't mean they aren't issues, though.

• VoIP doesn't work when the power is out
• VoIP doesn't have built-in 911
• VoIP can have network outages
• VoIP call quality problems
• VoIP and security

We have an article that explains these problems - and the solutions to these problems - associated with VoIP in specific: VoIP problems.