Most IP cameras support PoE (power over ethernet) - so what it means - it means that the camera can be powered using the same twisted pair cable as is used to transmit video (and in some cases, audio) signal.
There is, however, one but very significant condition - in order for PoE to work, the device your camera is connected to MUST be a PoE powered device.
99% of routers used for residential purposes (BT, Virgin, Vodafone etc.) are now PoE routers and they cannot therefore supply power over ethernet. If you plug your camera into such a router - nothing will happen, the camera will remain dead a Dodo. The same thing would happen (that, nothing...) if you plug the camera into a NON-POE NVR.
So, what are your options:
Option 1 (and most recommended) - get a simple PoE NVR. Hikvision DS-7604NI-K1/4P would be fine or, say, Dahua NVR5432-16P would work just fine.
Option 2 - use a PoE injector or Switch - e.g. DS-3E0318P-E.
Option 3 - use a 12VDC PSU.
LOL, sounds like a cry of desperation! 😁
Do people actually do that, stick their cameras into BT routers expecting them to work?
Sadly, much more often than you would think possible...