Aastra Telecom 57I CT, 55I, 53I manual Advanced

IP Phone Administrator Guide

Advanced Operational Features

Features	Feature	Description
	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
Operational		and all subsequent calls use the same authenticated
		connection. This significantly reduces the delay time when
		support the billing code feature.
		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	Allows you to enable or disable the addition of the
	Headers	User-Agent and Server SIP headers in the SIP stack.
	Multi-Stage Digit Collection (Billing Codes)	IP Phones support Sylantro Server features, like mandatory
	Support (for Sylantro Servers)	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
Advanced

6-4 41-001160-00, Release 2.1, Rev 04