Telephone Extension 23
or
Status Code 23

23 by itself is ambiguous. ICUC thinks you might have entered an unknown telephone number shortcut abbreviation or a telephone number extension without a preceding telephone number or a status code without any telephone number to apply the status code to. To make use of telephone number shorthand abbreviations you must first perform a login from this device. After login, depending upon how you have set up your account, here are some valid ways to use a pair of .ac digits:

23.ac Ex: Access web site of recent telephone number who's last two digits are 23
or
c.23.ac Ex: Calendar for last used telephone number ending in two digits 23
or
e.23.ac Ex: Email last used telephone number ending in two digits 23
or
i.23.ac Ex: Instant Message last used telephone number ending in two digits 23
or
s.23.ac Ex: Get status of last used telephone number ending in two digits 23
or
w.23.ac Ex: Access web site of recent telephone number who's last two digits are 23
or
x.23.ac Ex: Access web site of recent telephone extension who's last two digits are 23
or
800.555.1212.23.ac Ex: Access web site of telephone number 800.555.1212 extension 23
or
17.9797.800.555.1212.23.ac Ex: Set the status of telephone number 800.555.1212 x23 to status code 17 assuming that 9797 is a valid PIN code for performing status updates.

more information on telephone number shortcuts, extensions and status codes...