Global SIP Settings
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41-001343-02 REV05 – 07.2014
Use the following procedure to configure backup outbound proxies.
Limitations
The following are limitations with this feature:
•
Keep-alive mechanisms shall be limited to IPv4 only.
•
Per M5T, RFC5686 is not fully supported although the draft upon which it was based (draft-ietf-sip-outbound-15) is
supported.
SIP Server (SRV) Lookup
The SIP SRV Lookup feature allows you to configure the IP phone to issue a DNS query to retrieve records pertaining to a
SIP proxy, a SIP registrar, or a SIP outbound proxy.
The IP phone issues a DNS query for an SRV record when the IP address of the server is FQDN and the corresponding port
is 0.
For example, if the phone is configured with
sip proxy ip of "ana.aastra.com"
, and
sip proxy port of "0"
, the SRV
lookup may return multiple servers, based on the priorities if one is selected as primary and others are selected as sec-
ondary. However, if the IP address is an FQDN and the corresponding server port is non-zero, then the phone issues a
DNS "A" Name Query to resolve the FQDN into dot notation form.
If the IP address is a valid dot notation and the port is zero, then a default port 5060 is used.
You can configure SRV lookup using the configuration files (
aastra.cfg
and
<mac>.cfg
) only. The parameters to use are:
•
sip proxy ip
•
sip proxy port
Contact Header Matching
When sending SIP packets, the IP Phones observe the Contact header by matching the username, domain name, port,
and transport as referenced in SIP RFC 3261.This is called “strict SIP Contact header matching.” However, in specific net-
works (such as behind some SOHO routers), the phone registers with its private address in the Contact, but when the
response is sent back, the router maintains the public side IP address in the Contact header. This causes a non-matching
Contact header and the phone does not accept the new registration expiry timer.
You can set the parameter, “
sip contact matching
”, which allows the Administrator to specify the method used by the
phone to match the Contact Header. Previously by default, when sending SIP packets, the IP phones observed the con-
tact header by doing a full URI matching of username, domain, phone IP and port name, and transport (value=’0’). Now
the default value for the “
sip contact matching
” parameter is to match the username only (value=’2’). This parameter is
available via the configuration files only.
Enabling/Disabling the “Contact Header Matching” Feature
Use the following procedure to enable/disable the “Contact Header Matching” feature
.
Configuration Files
For the specific parameter you can set in the configuration files, see Appendix A, the section,
“Backup Outbound Proxy (Global Settings)”
on
and
“Backup Outbound Proxy (Per-line Settings)”
on
Note:
The phones only generate a ‘request’ and do
not
facilitate the ‘DNS or SRV service or provide a response to the requests.
Configuration Files
For the specific parameter you can set in the configuration files, see Appendix A, the section,