Casio phone dialer DBA-800 released in 1985.
Even though it is called a phone dialer, it does not have communication and calling functions like a smart watch.
So why “phone dialer”?
In fact, the speaker section at the center of the bottom can produce the "sound when dialing on a push-button line."

Push-line telephones use a sound called a tone to identify the destination of the call.
Therefore, even if you do not press the push buttons, if you play the "sound" that corresponds to each button, that sound will be identified as a tone signal and you can make a call.
A device that utilizes this function is the "phone dialer," which allows you to make a call by pressing the speaker against the handset and hearing a tone signal.

In the Showa era, when there were no mobile phones, when making a call from outside, it was common to look at the phone number registered on the wristwatch using the "data bank function" and then call the other party from a public phone.However, phone dialers were extremely streamlined because they allowed you to make a call using the phone number registered on your wristwatch.

However, a few years after the phone dialer was released, pagers began to gain popularity in Japan, and before long, flip phones and smartphones became widespread, leaving the phone dialer with no place to shine.
Unfortunately, public telephones, which were once a field of activity, are now on the verge of extinction in Japan.

However, you can still use phone dialers on most landlines (excluding IP phones).
The SEIKO T001, a watch that could watch TV released by Seiko at the same time, became completely unusable in Japan due to the end of analog broadcasting, so perhaps phone dialers are "happy as long as they can be used."