One weakness of VoIP phones is that, unlike analog phone systems, when the power goes out, your Internet service typically will also be deactivated. This is due to the fact that VoIP phones rely on Internet routers and modems that are connected to electrical outlets the same way a lamp or TV is connected to power. There is no electrical power coming from a battery or through the cable Internet wires to the phone. On the contrary, analog phone lines receive electricity from the same jack and wire that connect to the phone, so when the local power grid fails, the phone company still delivers backup power to the telephone. That is why it is important to have a backup phone or mobile phone in the event of a power outage, in case you need to call emergency services.