"Feature phones" is the term

If I am not mistaken, aren't dumbphones/flip phones/ feature phones vulnerable to stingray phone trackers?

If one is not encrypting their messages, then Law Enforcement Officers, nation-state actors and criminals can easily intercept SMS messages and phone calls.

Wikiless( an alternative front-end for Wikipedia):

https : / / wikiless(dot)org/wiki/Stingray_phone_tracker

Articles on Stingray phone tracker/imsi-catchers/ cell-site simulators:

https : / / www(dot)eff(dot)org/pages/cell-site-simulatorsimsi-catchers

https : / / theintercept(dot)com/surveillance-catalogue/stingray-iii/

Even more crazy(read the bolded statement, from The Intercept article):

Stingray I/II

Ground Based Geo-Location (Vehicular)

This dragnet surveillance workhorse has been deployed for years by numerous local law enforcement agencies across the United States. Don’t worry about the six-figure price tag: A federal grant will cover that. Upside: fierce name. Downsides: ensnares bystanders’ phones within up to 200 meters, drains phones’ batteries by forcing them to broadcast at full power for greater surveillance potential, and can block calls placed by nearby phones. But don’t worry too much: Ready-made non-disclosure agreements from the FBI and Harris Corp. will provide a pretext for concealing these features from the public. If you like the Stingray, you’ll love Harris Corp.’s next-generation Hailstorm, a must-have for cracking the 4G LTE network.