Grandstream Networks HT881

Default is No.
Use First Matching Vocoder in
200OK SDP
Includes only the rst matching vocoder in its 200OK response, otherwise it will include all matching vocoders
in same order received in INVITE.
Default is No.
Symmetric RTP
Changes the destination to send RTP packets to the source IP address and port of the inbound RTP packet
last received by the device. Default is No.
Enable RTCP Allows users to enable RTCP. The default setting is “Yes”.
Fax Mode
Species the fax mode: T.38 (Auto Detect) FoIP by default, or Pass-Through. If using Pass-through mode,
select preference codec as PCMU or PCMA.
Re-INVITE After Fax Tone Detected
Permits the unit to send out the re-INVITE for T.38 or Fax Pass Through if a fax tone is detected. Default is
Enabled
Jitter Buffer Type Selects jitter buffer type (Fixed or Adaptive) based on network conditions.
Jitter Buffer Length
High(initial 200ms, min 40ms, max 600ms)
Note: not all vocoders can meet the high requirement.
Medium(initial 100ms, min 20ms, max 200ms).
Low(initial 50ms, min 10ms, max 100ms).
SRTP Mode
Selects SRTP mode to use (“Disabled”, “Enabled but not forced”, or “Enabled and forced”). Default isDisabled
It uses SDP Security Description to exchange key. Please refer to
SDES:https://tools.ietf.org/html/rfc4568
SRTP:https://www.ietf.org/rfc/rfc3711.txt
SRTP Key Length Allows users to select supported SRTP Key Length.
Crypto Life Time Adds crypto life time header to SRTP packets. Default is Yes.
Analog signal line conguration
Caller ID Scheme Selects the caller id scheme, for example: Bellcore/Telcordia, ETSI-FSK …
Pulse Dialing Standard
Allows users to use Swedish pulse dialing standard or New Zealand pulse dialing standard.
Default isGeneral Standard.
Hook Flash Timing
Denes the time period when the cradle is pressed (Hook Flash) to simulate FLASH. To prevent unwanted
activation of the Flash/Hold and automatic phone ring-back, adjust this time value.
HT841/HT881 support a range from 40 to 2000 ms.
Default values are300minimum and1100maximum.
Gain
Adjusts the voice path volume.

•Rxis a gain level for signals transmitted by FXS
•Txis a gain level for signals received by FXS.
Default = 0dB for both parameters. Loudest volume: +6dB Lowest volume: -6dB.
User can adjust volume of call using the Rx gain level parameter and the Tx gain level parameter located on
the FXS port conguration page.
If call volume is too low when using the FXS port (ie. the ATA is at user site), adjust volume using the Rx gain
level parameter under the FXS port conguration page.
If voice volume is too low at the other end, user may increase the far end volume using the Tx gain level
parameter under the FXS port conguration PAGE.