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Signaling and Payload Payload Payload
framing (overhead) (voice) (voice) (voice)

Figure A-2. Trunking enabled
callerid
You can set a suggested Caller ID string for a user or peer with callerid. If you
define a Caller ID field for a user, any calls that come in on that channel will have
that Caller ID assigned to them, regardless of what the far end sends to you. If you
define Caller ID for a peer, you are requesting that the far end use that to identify
you (although you have no way of ensuring it will do so). If you want incoming
users to be able to define their own Caller IDs (i.e., for guests), make sure you do
not set the callerid field:
callerid=John Smith <(800) 555-1234>
defaultip
The defaultip setting complements host=dynamic. If a host has not yet registered
with your server, you’ll attempt to send messages to the default IP address config-
ured here:
defaultip=192.168.1.101
inkeys
You can use the inkeys option to authenticate a user with the use of an RSA key.
To associate more than one RSA key with a user channel definition, separate the
key names with a colon (:). Any one of those keys will be sufficient to validate a
connection. The “inkey” is the public key you distribute to your users:
inkeys=server_one:server_two
mailbox
If you associate a mailbox with a peer within the channel definition, voicemail will
send a message waiting indication (MWI) to the nodes on the end of that channel.
If the mailbox number is in a voicemail context other than default, you can specify
it as mailbox @ context. To associate multiple mailboxes with a single peer, use
multiple mailbox statements:
mailbox=1000@internal
outkey
You can use the outkey option to authenticate a peer with the use of an RSA key.
Only one RSA key may be used for outgoing authentication. The “outkey” is not
distributed; it is your private key:
outkey=private_key

348 | Appendix A: VoIP Channels