S621 Smartphone: what button so i use to get speakerphone...

Try clicking on the Speakerphone button ($) while on call and see if it's going to enable your speakerphone capability

Hi lucarna,
you can get unlock solution for your HTC S621 here http://www.mobileunlockguide.com/mobile-phone/4079/htc-s621/

No, you can only turn on the phone with the power button. If you feel comfortable opening the phone, then if you jump the front and back leg of the power switch, then it should turn the unit on if the switch is bad.

try here
http://forum.xda-developers.com/index.php

To perform a master/hard reset on your HTC S621 you will need to:

1. PRESS AND HOLD BOTH SOFT KEYS (Soft keys are the ones that are the defaults for Start and Contacts near the Green calling and Red end calling keys).
2. WHILE HOLDING DOWN SOFT KEYS, PRESS AND RELEASE THE POWER BUTTON, WAIT 3-5 SEC. (PHONE SHOULD POWER ITSELF ON BY DOING THIS)
3. RELEASE THE TWO KEYS SOFT KEYS.
4. WHEN SCREEN ON DASH LOOKS LIKE IT'S IN DOS FORMAT, PRESS SEND (GREEN ANSWER KEY)

Try upgrade the software on htc.com, it may be a bug. good luck

Try unistalling the software and instal back,might work

Contact the manufacturer by phone or e-mail , they should be able to assist.

FixYa forbids the distribution of Unlock codes / techniques.

Similar problem, with solution:
http://www.fixya.com/support/t1367687-htc_s621_also_known_as_htc_dash_or