As famously modded in 2600 mag, they were useful for a while...
https://phonelosers.com/redbox/tonedialer/
https://hackaday.com/2014/09/05/radioshack-phone-dialer-red-...
https://phonelosers.com/redbox/tonedialer/
https://hackaday.com/2014/09/05/radioshack-phone-dialer-red-...
And now that you remind me, that's totally why I bought one, but at the time I lacked the tools and electronics skills to do the mod.