VOIP is an excellent way of saving some serious money on phone/internet costs. It could be substitute/augment
both your landline/mobile phones" usage. I use it for my mobile phone as an extra number. The 3rd party service I use is
Google Voice.
Initially, I use my carrier's own number to sign up on the service. Google Voice is an separate app installed directly on my phone's screen which I tap on to select it when I want to use it over my carrier's service. It works quite well when decent WiFi is available either at home or out of the house. I use it as a back up when my carrier's own signal is too weak or unavailable to use. Or when I'm low on minutes.
Most of the time there is no charge to use this service. I don't have to get the other end user to sign up for this service unlike other 3rd party apps as most people have an Android phone which has Google products already installed.
Another reminder for all those people using alternate products to bypass pay TV options. Scan your channels frequently at least once a month-I do once a week when I remember to do so. Here in the US at least, the channels are migrating all the time to other frequencies/positions or whatever on the transmitting towers until 2020. Plus sometimes more channels are being added too. At my house, I keep losing/gaining channels all the time. Hope you don't experience channel loss!