+----+
    +---------------------->|IDLE|<----------------------------+
    |                       +-+--+                             |
    |                         |                                |
    |                         |  start                         |
    |                         |  channel                       |
    |                         v                                |
    |  channel error /     +--------+                          |
    |  session ends        | CHANNEL|                          |
    +----------------------+ SETUP  |                          |
    |                      +--+-----+                          |
    |                         |                                |
    |                         |  channel                       |
    |                         |  established                   |
    |  channel error /        v                 OPTIONS phase  |
    |  session ends         +-------+           failure        |
    +-----------------------+OPTIONS+--------------------------+
    |                       +-+-----+
    |                         |
    |                         |  OPTIONS phase
    |                         |  success
    |                         v
    |   channel error /    +---------+
    |   session ends       | ACTIVE  |
    +----------------------+         |
                           | +----+  +------------------+
                           | | MP |  |    send/receive  |
                           | +----+  |    CLUE messages |
                           |         |<-----------------+
                           | +----+  |
                           | | MC |  |
                           | +----+  |
                           |         |
                           +---------+