This object specifies the value of the Min-SE
header for INVITE messages originated by this
user agent and the minimum value of the
Session-Expires headers for INVITE messages
received by this user agent.
Any Session-Expires headers received with a
value below this object's value will be rejected
with a 422 client error response message.
Setting this object to a value less than 600 is
valid, but the possibly of excessive re-INVITES
and the impact of those messages should be fully
understood and considered an acceptable risk.