Casio G'z One User Manual page 135

Only one person can speak at a time during Push to
Talk calls. When using your phone keypad to make a
Push to Talk call, you must enter the ten-digit phone
number of the called party. Presence information may
not be available for all Push to Talk contacts. The
timeliness of presence information may be impacted
by the network registration status of a Push to Talk
contact. Your Push to Talk service cannot be used for
any applications that tether your phone to computers
or other devices for any purpose. Push to Talk-
capable phone and service required.
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