Available as an assembled Module and as a DIY project.
This Module is currently available.
DTMF Tone Generator
“My møm says I døn’t call her enøugh sø I made a mødule that wøuld dø it før me.” — Ross
https://www.moffenzeefmodular.com/bad-idea-1800callyermum
These merchants probably sell this module. Huh?
Included in 74 Racks, 43 are public: