Here’s a nostalgic look at the Sharp TM 20 (“Mobile Mail”).
The pocket email device that predates modern smartphones but laid groundwork for mobile messaging as we know it.

Released in 1998 and manufactured by Sharp for the TelMail/PocketMail system.
A dedicated mobile email PDA: no camera and no apps just an email, address book, calendar, memo pad, and alarm.
Acoustic coupler modem built in, you would dial a toll free number on a landline or
payphone, then hold the device up to the handset top to the receiver, bottom to the transmitter.
After a 1 minute of squawks, messages would sync via 14.4 kbps transfer, limited by 4,000 characters per message.
Powered by two double A batteries lasting 70 – 150 hours depending on use.
PocketMail service was eventually discontinued, and with the demise of public payphones, the system became obsolete.

Design & Features:
• Dimensions: Approx 6.4 × 3.2 × 1 inches (16 × 8 × 2.4 cm) Weight (8.5 oz) (270 g)
• Flip-up lid with dot-matrix LCD (239×80 px) and full QWERTY keyboard, including a dedicated “@” key.
• Status LEDs to indicate connection progress, and a blue button to initiate sync.
• PC sync via serial RS 232 cable for backups or PC interface.

Sharp TM-20 Service Manual.