Specifications

sip_signaling_features.fm
A31003-H8022-F100-2-7618, October 2006
HiPath 8000 V2.2, Feature Description Guide
16-9
SIP Signaling Features
SIP Over TCP/TLS Support
16.14 SIP Over TCP/TLS Support
16.14.1 Definition
The SIP over TCP/TLS support feature provides SIP over TCP and SIP over TLS, in
accordance with RFC 3261.
The TCP-TLS-UDP dispatcher (TTUD) process is implemented to provide UDP, TCP, and TLS
or SSL transport services for:
● SIP
● CSTA
● Any other application requiring TCP, SSL, or UDP connectivity
The TTUD process is designed to be independent of the application protocol used over the
basic transport service of UDP, TCP, or TLS/SSL and to provide services to multiple diverse
applications at the same time.
16.14.2 Functional Operation
The HiPath 8000 complies with the TLS security mechanisms defined for SIP in RFC 3261,
including section 26.3.2.1, which requires the HiPath 8000 to reuse the TCP/TLS connection
that is established by the SIP endpoint. The TCP/TLS connection that is established by the SIP
endpoint during SIP registration must be kept open and reused for all SIP transactions that
occur between the HiPath 8000 and the SIP endpoint. The responsibility to keep this TCP/TLS
connection open rests solely with the SIP endpoint.
It is not possible for the HiPath 8000 server to re-establish the TCP/TLS connection toward the
SIP endpoint if it fails. This is because RFC 3261 does not require SIP endpoints to support
TLS server functionality. For example, as with most SIP telephones, the optiPoint 410 S SIP
telephone only supports TLS client functionality and does not support TLS server functionality.
The HiPath 8000 server must rely on the SIP endpoint to establish the TCP/TLS connection
when it fails. If the TLS connection fails, the HiPath 8000 cannot deliver SIP messages to the
SIP endpoint—for example, it cannot deliver an incoming call to the SIP endpoint.