User guide

Chapter 17: AltiGen IP Phone Configuration
MAXCS ACC 6.7.1 Administration Manual 217
Debug
This is for debugging the IP phone using Telnet. You need to enter a
Diagnostic password when logging in to MaxAdmin (before you enter your
Admin password) to enable this configuration.
SIP Transport
These settings secure the SIP signaling messages and the RTP. SIP
signaling is secured using transport layer security (TLS). RTP or SIP-
associated media is secured using the secure RTP (SRTP) protocol.
• Persistent TLS – Check this setting to have the selected extension
communicate using TLS. The TLS protocol allows applications to com
-
municate across a network in a way designed to prevent eavesdropping,
tampering, and message forgery. TLS provides endpoint authentication
and communications privacy for VoIP systems using cryptography.
If either side initiates SIP messaging with an alternate transport like
UDP or TCP, these are supported, as well.
Note: If Persistent TLS is checked for a third-party IP phone, you also
need to configure the phone, itself, for TLS. If the third-party
phone initiates a UDP SIP message, and Persistent TLS is
checked in MAXCS, then the SIP connection will fail.
• SRTP – Check this setting to have the selected extension use SRTP.
SRTP is a version of RTP that provides confidentiality and message
authentication. Since the SRTP session key is sent in the SIP signaling
via SDP, the key can be exposed to eavesdropping. So SRTP needs to
co-exist with TLS for the communication to be fully secure.
If SRTP is checked, the voice stream always goes through the server.
If the IP phone is behind NAT, UDP will be used even if TLS and SRTP are
checked, since TLS cannot penetrate NAT.
IP Phone Configuration vs Enterprise Manager configuration:
SIP calls from one Altigen server to another go through a SIP Tie Trunk.
Configuring TLS for this scenario is done in Enterprise Manager. See “
SIP
Transport” in the table on page 305.
Extension level policy has priority over the codec profile policy.
If the IP extension supports TLS and the codec profile set in Enterprise
Manager does not, then the IP extension policy holds. That way you can
configure a range of IP addresses in the IP Dialing table or IP Codec screen,
and have only a few IP addresses/extensions support TLS.
If the IP extension does not have TLS configured as its transport, but the
codec profile supports TLS for that extension, then the codec profile policy
holds.
Time Display
• Offset – a per phone-based configuration that allows a remote IP
phone to display a different time, based on location. The offset is the
time difference, in hours, between the AltiGen system and the IP phone.
• Format – a per-phone-based configuration that allows the IP phone to
display the time in one of the following formats: 24 hour (example:
13:15), 12 hour AM/PM (example: 1:15 PM), or AM/PM 12 hour
(example: PM 1:15).
Parameter Description