state
call.state contains in what state call is in: 
call.state is a numerical value of enum call.stat. To get a string representation of current state use call.getCallState()
call.state can have the following call.stat values:
- new_rcvd (70) a new SDP has been received during call
- new_snt (60) a new SDP has been sent during call
- talking (50) in call, media flows between endpoints
- esc_rcvd (40) partner has ended call, hung us up
- esc_snt (30) we have ended call, hanging up
- answer_rcvd (24) outgoing call, answer SDP received
- early_rcvd (23) outgoing call, early media received
- ring_rcvd (22) outgoing call, ringing received (phone rings at remote end)
- offer_snt (21) outgoing call, offer SDP sent
- calling (20) user has initiated an outgoing call
- answer_snt (14) incoming call, answer SDP sent
- accepted (13) incoming call has been accepted by user
- preanswer_snt (12) incoming call, preliminary answer SDP has been sent
- preanswer (11) incoming call, preliminary answer requested
- offer_rcvd (10) incoming call, offer SDP received
- waiting (2) waiting for local media
- idle (1) ready to send/receive calls
- disabled (0) not ready for use, do not use call object
