How many substitutions does a team get, and how are they requested?

• 18 team substitutions per set.
• The head coach requests substitutions, verbally or with the hand signal. A substitute entering the substitution zone also counts as a request.
• Only one substitution request per team per dead ball, even if a timeout is also granted.
• An illegal substitution request is an unnecessary delay.
• The scorer tells the second referee when a team uses its 15th through 18th substitutions, and the second referee informs the coach.
• An exceptional substitution (for an injured, ill or disqualified player when no legal substitute is available) counts as a team substitution if fewer than 18 have been used. The player replaced may not return in that set.
• If a starting player is injured or ill before a set after the lineup is in, that player is replaced in the lineup without penalty and no entry is charged.

Libero replacements are not substitutions and don't count toward the 18.