Avaya IP Softphone Getting Started Manual page 3

Avaya IP Softphone requires an extension on the telephone system that is
administered for any of the following display telephones:
2420
4624
6416D+
8411D
Avaya IP Softphone supports the telephones listed. However, Avaya IP Softphone may
operate properly with other 6400 Series and 8400 Series telephones. Also, if your
extension has a non-display telephone, your System Administrator should administer
your extension as a display telephone. For example, if your extension has an 8410B
telephone (which is a non-display telephone), your System Administrator should
administer your extension as an 8410D telephone (which is a display telephone).
Expansion modules are supported when configured for the 2420, 4620, 6416D+,
6424D+, and 8434D telephones.
NOTE:
Avaya IP Softphone does not support data modules. If your extension has a
data module configured, you must either have your System Administrator
disable it or get a different IP Softphone extension to log into on the server.
Telephones Supported
4602 4606
4630 6402D
6424D+ 8405D
8434D
4612 4620
6408D 6408D+
8405D+ 8410D