sverweij/mscgen_js

# SIP protocol with an intermediate proxy (source: wikipedia)
Alice, P1, P2, Bob;

Alice -> P1 : INVITE;
Alice <- P1 : 100 Trying;
P1 -> P2 : INVITE;
P1 <- P2 : 100 Trying;
P2 -> Bob : INVITE;
P2 <- Bob : 100 Trying;
P2 <- Bob : 180 Ringing;
P1 <- P2 : 180 Ringing;
Alice <- P1 : 180 Ringing;
--- : Alice's client plays ringing;
...;

--- : Bob answers;
P2 <- Bob : 200 Ok;
P1 <- P2 : 200 Ok;
Alice <- P1 : 200 Ok;
Alice -> P1 : ACK;
P1 -> P2 : ACK;
P2 -> Bob : ACK;
--- : two way media;
...;

--- : Bob hangs up;
P2 <- Bob : BYE;
P2 -> Bob : 200 Ok;
P1 <- P2 : BYE;
P1 -> P2 : 200 Ok;
Alice <- P1 : BYE;
Alice -> P1 : 200 Ok;