NOSUMMON

Usage: nosummon

all characters have SUMMON PROTECTION turned on by
default.  This prevents people from summoning you and gives you a warning
message if someone tries.  If you want to let someone summon you (i.e. if
someone wants to summon you for a legitimate reason), type NOSUMMON to turn
off summon protection.  You can then type NOSUMMON again to turn protection
back on.