SEAS module enables OpenSER to transfer the execution logic control of a sip
message to a given external entity, called the Application Server. When the
OpenSER script is being executed on an incoming SIP message, invocation of
the as_relay_t() function makes this module send the message along with some
transaction information to the specified Application Server. The Application
Server then executes some call-control logic code, and tells OpenSER to take
some actions, ie. forward the message downstream, or respond to the message
with a SIP repy, etc