Climm

climm (previously mICQ) is a free CLI-based instant messaging client that runs on a wide variety of platforms, including AmigaOS, BeOS, Windows (using either Cygwin or MinGW), OS X, NetBSD/OpenBSD/FreeBSD, Linux, Solaris, HP-UX, and AIX.
Functionality.
climm has many of the features the official ICQ client has, and more:
climm also supports basic functionality of the XMPP protocol.
History.
"Climm" was originally developed as "mICQ" by Matt D. Smith as public domain software. Starting with mICQ 0.4.8 it was licensed under the GPLv2, not much of the original PD code remained since then. All later additions were made by Rüdiger Kuhlmann, in particular, the support for the ICQ v8 protocol. mICQ was renamed to climm ("Command Line Interface Multi Messenger") with version change to 0.6. CLimm was relicensed to include the OpenSSL exception.