LONDON (AP) — Thousands of Britain's iconic red phone boxes will be protected from removal under new rules, the U.K.'s telecommunications regulator said Tuesday.

The public payphone boxes may look like obsolete relics in an age of ubiquitous smartphones, but regulator Ofcom said they can still be a "lifeline" for people in need.

The regulator is proposing rules to prevent 5,000 call boxes in areas with poor mobile coverage from being closed down. It said that phone booths in areas considered accident or suicide hotspots, and those that have had more than 52 calls made from them in the past 12...