Page 378 - Asterisk™: The Future of Telephony

SIP

Just as with IAX, the SIP configuration file (sip.conf) contains configuration information
for SIP channels. The headings for the channel definitions are formed by a word framed
in square brackets ([])—again, with the exception of the [general] section, where we
define global SIP parameters. Don’t forget to use comments generously in your
sip.conf file. Precede the comment text with a semicolon; everything to the right will
be ignored.

General SIP Parameters

The following options are to be used within the [general] section of sip.conf:
allowexternalinvites
If set to no, this setting disables INVITE and REFER messages to non-local do-
mains. See the domain setting.
allowexternalinvites=yes|no
allowguest
If set to no, this disallows guest SIP connections. The default is to allow guest
connections. SIP normally requires authentication, but you can accept calls from
users who do not support authentication (i.e., do not have a secret field defined).
Certain SIP appliances (such as the Cisco Call Manager v4.1) do not support au-
thentication, so they will not be able to connect if you set allowguest=no:
allowguest=no|yes
allowoverlap
If set to no, overlap dialing is disabled:
allowoverlap=no|yes
allowsubscribe
Specifies whether or not to allow external devices to subscribe to extension status
(as set in the hint priority). Defaults to yes:
allowsubscribe=yes|no
allowtransfers
If set to no, transfers are disabled for all SIP calls, unless specifically enabled on a
per-user or per-peer basis:

allowtransfers=no|yes
alwaysauthreject
If this option is enabled, whenever Asterisk rejects an INVITE or REGISTER, it
will always reject it with a 401 Unauthorized message instead of letting the caller
know whether there was a matching user or peer for his request:
alwaysauthreject=no|yes

350 | Appendix A: VoIP Channels