Synopsis:
   summon <user>[@<server>]

Description:
   SUMMON, as its name indicates, is used to summon someone to irc.  It
   most resembles a Unix talk request, except the user is prompted to join
   the irc network instead of initiate a talk connection.

   Note that the input must be the recipient's username (e.g. login name).
   Irc servers on the networks are the only hosts that can be directed to
   issue a SUMMON.  If no irc server is specified, the current is used.

Other Notes:
   As with USERS, this command outlived its usefulness years ago.  It is
   one of the few remaining relics from the days when the only irc users
   were those with local servers.  Few, if any, servers have this feature
   enabled anymore.