You’re gonna need to unpack what you mean here because TCP/IP is the basis for pretty much everything, even modern phones
Phones, like landline phones or when you’re not using wifi calling, use a totally different method of communication than the internet. VoIP and WiFi calling do not use the phone part, they use the internet and are a completely different protocol/method.
Alrighty let’s learn some vocab
POTS lines, aka plain old telephone system, are what you’re referring to when you say landlines
When you’re calling off of Wi-Fi, most of the time you’re using a technology called VoLTE- Voice over LTE, which still functions on top of TCP/IP
The difference that matters here is the VoIP and VoLTE, as well as Wi-Fi calling are all digital protocols over TCP/IP networks.
If you really wanna get specific, most digital phone systems use protocols called Telephony, and SIP(session initiation protocol)
Shame the article was talking about a mobile phone or that point would have mattered…
