AT&T Merlin Legend MLX-20L Operation Manual page 109

Programming Special
A
Characters
When you program your Personal Directory, you are storing
a sequence of numbers to be dialed automatically.
Some sequences need special characters to separate the
digits and signal that a certain function should begin. These
characters signal the system to pause and wait for a response
to the dialed digits, to stop so you can enter a credit card
number or password, or to signal that a call is coming in.
Ask your system manager which special characters are
needed and when to use them. Also, see "Directory" in
Chapter 4.