We still have a landline (technically VoIP) phone. There's also a list of important phone numbers written on the fridge. Good for emergencies.
There are few things more nerve wracking than frantically trying to find your cell phone and the number for poison control after your kid just swallowed something they shouldn't have.
Most landline phones for sale in the UK need external power, I would say. Either they are a base station with a wireless handset, or they have an answering machine, or phonebooks and other functionality that needs extra power. Maybe I'm mistaken, but I don't really see "just a phone" any more. Not that I've purchased a phone in like 8 years
It's fortunate where I live that poison control just uses the standard emergency services number.
I can't imagine how hard it must be to recall the number during an emergency where time is a factor. Particularly if the number is like 0118 999 881 999 119 725… 3