Spectralink 84-Series Series Wireless Telephones Administration Guide
1725-86984-000_P.docx
September 2016
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This would result in an offer (SIP INVITE with SDP) with 8 crypto attributes with the following
session parameters:
<no session parameters
>
UNENCRYPTED_SRTCP UNENCRYPTED_SRTP
UNAUTHENTICATED_SRTP
UNAUTHENTICATED_SRTP,UNENCRYPTED_SRTCP
UNENCRYPTED_SRTP,UNENCRYPTED_SRTCP
UNAUTHENTICATED_SRTP,UNENCRYPTED_SRTP
UNAUTHENTICATED_SRTP,UNENCRYPTED_SRTP,UNENCRYPTED_SRTCP
In the above example, the crypto attri
butes are ordered “most secure” to “least secure” (more
security turned off). The handset receiving this call should chose the most secure crypto it can
support based on the SRTP
“require” settings and reply with it in the SDP of a 200 OK SIP
message.
In Example 2, the srtp_2.cfg configuration file is shown below:
This would result in an offer (SIP INVITE with SDP) with 4 crypto attributes with the following
session parameters:
UNENCRYPTED_SRTP UNENCRYPTED_SRTP,UNENCRYPTED_SRTCP
UNAUTHENTICATED_SRTP,UNENCRYPTED_SRTP
UNAUTHENTICATED_SRTP,UNENCRYPTED_SRTP,UNENCRYPTED_SRTCP
In the above example, every crypto includes the
UNENCRYPTED_SRTP
session parameter
because it is required.
If nothing compatible is offered based on the receiving handset
’s STRP “require” settings, then
the call is rejected or dropped.
Server Redundancy
Server redundancy is often required in VoIP deployments to ensure continuity of phone service
if, for example, the call server needs to be taken offline for maintenance, the server fails, or the
connection between the handset and the primary server fails.
Terminology
Before you read this section, take a moment to familiarize yourself with the following definitions: