Psion Inc 7505BTHC25 ユーザーズマニュアル

Tapping on SMS Configuration opens the SMS configuration dialog. The SMS Centre 
Address follows the same rules as the recipient's phone number in the New message dialog. 
The Message Validity Period parameter is sent to the SMS Centre with each message sent 
subsequently and instructs the SMS Centre on how long it should attempt to deliver the 
message to the recipient (the SMS Centre may impose an upper limit on the validity period 
regardless of the setting).

The user interface tries to keep the SMS storage location available for a new incoming 
message if the Delete oldest message when full checkbox is checked. In this case, when a 
new message arrives and the SMS storage becomes full, the oldest received message is de-
leted. If any string is entered as the Message Suppression Prefix, messages beginning with 
that string will not be shown in either the Inbox or Outbox. In this way, messages intended 
for another application running on the same device can be hidden.