Aastra Dialog 4220 Lite User Manual page 17

Note: The programmed number may consist of a maximum
of 20 digits plus
the public network.
To erase one programmed number:
Dial and press selected digit.
Press
To erase all programmed numbers:
Dial
Press
Dial by a function key
Both functions and phone numbers can be programmed
on a function key. To programme a key, speak to your
system administrator.
Press the function key.
Ericsson Dialog 4222
which indicates the second dial tone from
16