There were still firms that had Telex into the 21st century. Mostly firms that had binniss in obscure countries that still relied on telex.
It seems that's all gone now, butt I know that some firms kept their telex and telex address into the 2000s.
Even in the late '90s, sometimes the best way to ensure a communication to/from a place like Benin was to use Telex. You knew it was received. More reliable than mail, fax, phone, or messenger (physical messenger - not text message - like FedEx or DHL) in some areas of the world.