IPTV is a generic term and encompasses many different technologies. It just means the video stream is coming over Internet Protocol as opposed to legacy cable transmission, but says nothing about the format/authentication used. Each IPTV implementation is different and they are not compatible with each other.
Uverse IPTV uses a proprietary IPTV format and requires a cable box.
HDHR Premium TV also used their own proprietary IPTV format and required a HDHR box.
Spectrum probably uses standard web streaming technology with proprietary authentication, and requires that you use their app or website.
Countries like UK and NZ have started offering web streams of many OTA channels, which is also referred to as IPTV.
Many dubious IPTV services also exist, which offer legally-questionable streams in a semi-standard m3u format.
The only "IPTV" supported by Channels is the TV Everywhere system, which uses standardized web streams and standardized authentication that works across all major US cable providers and networks.
For other "IPTV" sources, we have no plans to add support. You can check out a project like xteve or Telly to do your own integration, but your mileage will vary and we do not officially support those setups.