Page 390 - Asterisk™: The Future of Telephony

can be overridden with the fromuser option. This allows a channel definition to be
referenced with a name other than that used to authenticate:

fromuser=john_smith
host (peer)
This configures the host to which this peer is to connect. Use a fully qualified
domain name:
host=remote.hostname.tld
incominglimit (both)
This option limits the total number of simultaneous calls for a peer or user. It sets
the max number of simultaneous outgoing calls for a peer, or the max number of
incoming calls for a user.

incominglimit=3
insecure (both)
When an INVITE is received from a remote location, Asterisk attempts to authen-
ticate the string of characters before the @ sign on the INVITE line received in the
SIP header with the name of a channel definition in sip.conf. If the remote end is a
user agent, it will authenticate based on a user definition. However, if the remote
end is a SIP proxy service, it will authenticate on the peer entry. When calls come
from a provider such as Free World Dialup, which acts as a proxy for the true
remote end who is calling you, that provider cannot authenticate the call on behalf
of the endpoint. Since it would be impractical to have an authentication configured
for every FWD user, and since FWD cannot respond to a 407 Proxy Authentication
Required response, there must be an alternate way to allow calls from these callers.
If you set insecure=invite, you’ll determine which peer to match on by comparing
the IP address or hostname and port number to those provided in the Contact field
of the SIP header with the host and port options in sip.conf. If a match is found,
authentication will not be required on the initial INVITE, and the call will be al-
lowed.
If you have multiple endpoints behind a NAT device, you need to enable inse
cure=port to match against only the IP address. To not require authentication on
the incoming INVITE for the peer, set insecure=invite,port:
insecure=invite
language (both)
This sets the language flag to whatever you define. The global default language is
English. The language that is set is sent by the channel as an information element.
It is also used by applications such as SayNumber() that have different files for dif-
ferent languages. Keep in mind that languages other than English are not explicitly
installed on the system, and it is up to you to configure the system to ensure that
the language you specify is handled properly:

362 | Appendix A: VoIP Channels