Linksys SPA942 Using SPA9x2 Phones in a VLAN, Determining the Type of NAT Used on Your Router

Introducing Linksys SPA9x2 Phones

Using SPA9x2 Phones in a VLAN

•If the device is another SIP UA, the information is carried in the Contact header and the Session Description Protocol (SDP) embedded in SIP message bodies. The VIA header in outbound SIP requests might also need to be substituted with the public address if the UAS relies on it to route back responses.

NOTE: SDP defines a text-based format for describing streaming media sessions and multicast transmissions. SDP is not a transport protocol but a method of describing the details of the transmission. For example, an SDP file contains information about the format, timing and authorship of the transmission, name and purpose of the session, any media, protocols or codec formats, the version number, contact information and broadcast times.

•Extends the discovered NAT mappings by sending keep-alive packets. Because the mapping is alive only for a short period, the SPA9x2 continues to send periodic keep- alive packets through the mapping, as needed.

Determining the Type of NAT Used on Your Router

To determine the type of NAT your router uses, enable debugging on the SPA9x2:

1.Make sure you do not have firewall running on your PC that could block the syslog port (by default this is 514).

2.Log on to the phone’s web UI. For information about this, see ”Using the Web User Interface” section on page 20.

3.Click Admin Login > advanced.

4.Click the System tab, then set Debug Server to the IP address and port number of your syslog server. Note that this address and port number has to be reachable from the SPA9x2. This port number appears on the output file name. The default port number is 514.

5.Set Debug Level to 3. Do not change the value of the Syslog Server parameter.

6.To capture SIP signaling messages, click the Ext tab.

7.Set SIP Debug Option to Full. The default output is named syslog.514.log (if not port number was specified).

8.To collect information about what type of NAT your router uses click the SIP tab and scroll to NAT Support Parameters.

9.Back in the System tab, select yes in the STUN Test Enable drop-down box,

View the debug messages to determine if your network uses symmetric NAT. Look for the Warning header in REGISTER messages, for example, Warning: 399 Spa “Full Cone NAT detected.”

Using SPA9x2 Phones in a VLAN

If you use a VLAN your SPA9x2 voice packets are tagged with the VLAN ID.

Linksys SPA9x2 Phone Administration Guide 14