•the Services, Inbox, Outbox

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IP Phone E restrictions
Service package restrictions
Individual features and feature restrictions are sent to the IP Phone 1140E
as apart of the service package every time a particular user logs onto the IP Phone E. If the call server does not support service packages,
or if the call server restricts some of the features in the service package,
functionality of some features is restricted.
If functionality is restricted, the associated buttons and Context-sensitive soft keys are not accessible or do not respond.
Distinctive Ringing feature
The IP Phone E does not support the CS 2000 and CS 2100 Distinctive
Ringing feature.
SIP Firmware Release 1.1 for IP Phone E Administration
NN43113-300 Standard May Copyright © 2008, Nortel Networks

102
IP Phone E restrictions
SIP Firmware Release 1.1 for IP Phone E Administration
NN43113-300 Standard May Copyright © 2008, Nortel Networks

103
NAT firewall traversal
The objective of putting devices behind a Network Address Translator (NAT)
is to protect the devices from external interruption and to extend the public IP
address space. However, the shield to stop unsolicited incoming traffic also has the drawback of breaking a number of IP applications, including SIP.
If a device is behind a NAT, transport addresses obtained are not publicly routable, and therefore, not useful in a number of multimedia applications.
The limited lifetime of the NAT port mapping can also cause the SIP
signaling to fail. If a port mapping is idle, it can be released by the NAT
and reassigned to other applications.
The STUN protocol lets an IP Phone E discover the presence and type of NATs between the IP Phone E and the public Internet. In addition, an IP Phone E can discover the mapping between the private IP address and port number and the public IP address and port number. Typically, a service provider operates a STUN server in the public
Internet, with STUN-enabled IP Phones embedded in end-devices, which are possibly behind a NAT.
A STUN server can be located using DNS SRV records using the domain of the service provider as the lookup. STUN typically uses the well-known port number 3478. STUN is a binary encoded protocol with a octet header field and possibly additional attributes. The STUN protocol learns the public
IP addresses, and therefore, some security is necessary.
To initiate a STUN lookup, the IP Phone E sends one or more Binding
Request packets using UDP to the STUN server. These packets must be sent from the same IP address that the IP Phone E uses for the other protocol, because this is the address translation information that the IP
Phone E tries to discover.
The server returns Binding Response packets, which tell the IP Phone
1140E the public IP address and port number from which it received the
Binding Request. The IP Phone E knows the private IP address and port number it used to send the Binding Request, and therefore, it learns the mapping between the private and public address space being performed by the NAT. If the Binding Response packets indicate the same address and port number as the request, the IP Phone E knows no NATs are present.
SIP Firmware Release 1.1 for IP Phone E Administration
NN43113-300 Standard May Copyright © 2008, Nortel Networks

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