User's Manual

Configura
tion
Description Expected result Possible results
None:
unsupport
ed
Unsupported Unsupported Unsupported
Note:
The server must be configured with the appropriate protocols enabled for the success
condition to be realized. Failure results are possible if the server configuration is changed
to disallow protocols.
Managing connection persistence
The IP Deskphone attempts to establish and maintain a persistent connection with the proxy
when TCP and TLS are active protocols. After this connection is established, the IP Deskphone
sends all outgoing connections over this persistent connection.
SIP IP Deskphones and servers, which use UDP to communicate, listen for incoming
connections on known ports, and originate each request on a randomly selected UDP port.
Even if TCP is used, new requests can potentially be sent using a new source port unless the
connection between the IP Deskphone and proxy is kept active.
Connection persistence does the following:
• Keeps a connection established between a client and the outgoing proxy.
• Reuses the open connection for future incoming and outgoing requests.
Figure 37: Incoming/Outgoing with connection reuse
When using UDP, an IP Deskphone behind a firewall must periodically send a request to the
server to maintain an open pinhole in the firewall so that the server can contact the IP
Deskphone when sending requests.
When using TCP/TLS and connection persistence, it is not necessary to send a SIP_PING to
the server in order to keep a pinhole alive, and the keep-alive mechanism is reduced to a
method which involves significantly less overhead.
Managing connection persistence
SIP Software for Avaya 1100 Series IP Deskphones-Administration November 2012 235