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Grandstream Networks, Inc. HT–496 User Manual Page 24 of 33
Firmware 1.0.3.64 Last Updated: 1/2007
modes supported: 1) in audio which means DTMF is combined in audio signal
(not very reliable with low-bit-rate codec), 2) via RTP (RFC2833), or 3) via SIP
INFO. Multiple selections of DTMF method are supported.
Send Flash Event
Default is No. If set to yes, flash will be sent as DTMF event.
Enable Call Features
Default is Yes. Advanced call features and feature codes functions are
supported locally.
Use Bell-style 3-way
Conference
Enables Bellcore Style 3-way Conference if parameter is set to “Yes”. *23 is
disabled.
Off-hook Auto-Dial
This parameter automatically configures and dials User ID or extension
number upon off-hook. Only the user part of a SIP address needs is entered
here. The HT–496 will automatically append the “@” and the host portion of
the corresponding SIP address.
Proxy-Require
SIP Extension to notify SIP server that the unit is behind the NAT/Firewall.
Disable Call Waiting
Default is No.
NAT Traversal (STUN)
This parameter defines whether the HT–496 NAT traversal mechanism is
activated or not. If activated (by choosing “Yes”) and a STUN server is also
specified, then the HT–496 performs according to the STUN client
specification. Under this mode, the embedded STUN client will detect if and
what type of firewall/NAT is used. If the detected NAT is a Full Cone,
Restricted Cone, or a Port-Restricted Cone, the HT–496 will use its mapped
public IP address and port in all of its SIP and SDP messages.
If the NAT Traversal field is set to “Yes” with no specified STUN server, the
HT–496 will periodically (every 20 seconds or so) send a blank UDP packet
(with no payload data) to the SIP server to keep the “hole” on the NAT open.
No Key Entry Timeout
Default is 4 seconds.
Preferred Vocoder
The HT–496 supports up to 6 different Vocoder types including G.711 A-/U-
law，G.723.1, G.726, G.729A/B, iLBC.
Users can configure Vocoders in a preference list included with the same
preference order in SDP message. The first Vocoder in this list is the
appropriate option in “Choice 1”. The last Vocoder in this list is the appropriate
option in “Choice 6”.
Voice Frames per TX
Number of voice frames transmitted in a single packet. User should be aware
of the requested packet time (used in SDP message). This parameter is
associated with the first vocoder in the Vocoder Preference List or the actual
payload type negotiated between the 2 conversation parties at run time.
e.g. if the first vocoder is configured as G.723 and the “Voice Frames per TX”
is set to 2, then the “ptime” value in the SDP message of an INVITE request
will be 60ms because each G.723 voice frame contains 30ms of audio.
If the configured voice frames per TX exceeds the maximum allowed value,
the HT–496 will use and save the maximum allowed value for the
corresponding first vocoder choice.
The maximum value for PCM is 10(x10ms) frames;
• for G.726, it is 20 (x10ms) frames; .
• for G.723, it is 32 (x30ms) frames;
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