Aastra Telecom SIP 57I - Manual (Page 442)

Advanced Operational Features
6-4 41-001160-00, Release 2.1, Rev 04
IP Phone Administrator Guide
Advanced Operational Features
Transport Layer Security (TLS) Allows you to enable or disable the use of Persistent
Transport Layer Security (TLS).
Persistent TLS sets up the connection to the server once
and re-uses that connection for all calls from the phone. The
setup connection for Persistent TLS is established during the
registration of the phone. If the phones are set to use
Persistent TLS, and a call is made from the phone, this call
and all subsequent calls use the same authenticated
connection. This significantly reduces the delay time when
placing a call.
Symmetric UDP Signaling Allows you to enable or disable the phone to use port 5060
to send SIP UDP messages.
Removing UserAgent and Server SIP
Headers Allows you to enable or disable the addition of the
User-Agent and Server SIP headers in the SIP stack.
Multi-Stage Digit Collection (Billing Codes)
Support (for Sylantro Servers) IP Phones support Sylantro Server features, like mandatory
and optional billing codes that require the application server
to notify the phone to collect more digits before completing
the call. The IP phone is able to collect digits in two stages to
support the billing code feature.
Feature Description