User Guide
Grandstream Networks, Inc.  HT-502 User Manual  Page 23 of 31 
  Firmware 1.0.0.29  Last Updated: 01/2007 
Use # as Dial Key 
Allows users to configure the “#” key as the “Send” (or “Dial”) key. If set to 
“Yes”, “#” will send the number. In this case, this key is essentially 
equivalent to the “(Re)Dial” key. If set to “No”, this “#” key can be included 
as part of number. 
Subscribe for MWI 
Default is No. When set to “Yes” a SUBSCRIBE for Message Waiting 
Indication will be sent periodically. 
Send Anonymous 
If this parameter is set to “Yes”, the “From” header in outgoing INVITE 
message will be set to anonymous, blocking Caller ID. 
Special Feature 
Default is Standard. Choose the selection to meet some special 
requirements from Softswitch vendors. 
Preferred Vocoder 
The HT–502 supports up to 5 different Vocoder types including G.711 A-
/U-law, GSM, G.723.1, G.729A/B. The user can configure Vocoders in a 
preference list that will be included with the same preference order in SDP 
message. The first Vocoder is entered by choosing the appropriate option 
in “Choice 1”. The last Vocoder is entered by choosing the appropriate 
option in “Choice 8”. 
G723 Rate 
Defines the encoding rate for G.723 vocoder. By default, 6.3kbps rate is 
chosen. 
iLBC Frame Size 
Sets the iLBC frame size in 20ms or 30ms 
iLBC Payload type 
Defines payload type for iLBC. Default value is 97. The valid range is 
between 96 and 127. 
G726-16 Payload type 
Default value is 98. Range is from 96 to 127. 
G726 - 24 Payload type 
Default value is 99. Range is from 96 to 127. 
G726 - 32 Payload type 
Default value is 100. Range is from 96 to 127. 
G726 - 40 Payload type 
Default value is 103. Range is from 96 to 127. 
G729E payload type 
Default value is 102. Range is from 96 to 127. 
VAD 
Default is No. 
Fax Mode 
T.38 (Auto Detect) FoIP by default, or Pass-Through (must use codec 
PCMU/PCMA) 
Jitter Buffer Type 
Select either Fixed or Adaptive based on network conditions. 
Jitter Buffer Length 
Select Low, Medium or High based on network conditions. 
SLIC Setting 
Dependent on standard phone type (and location) 
Caller ID Scheme 
• Bellcore/Telcordia 
• ETSI-FSK 
• ETSI-DTMF 
• SIN 227 - BT 
• NTT Japan 
Polarity Reversal 
Default is No. If set to “Yes”, polarity will be reversed upon call 
establishment and termination. 
Hook Flash Timing 
If the timing is shorter than “minimum”, it is considered Ignore. 
If the timing is longer than “minimum” but shorter than “maximum”, it 
is considered Flash. 
If the timing is longer than “maximum”, it is considered Hand-up. 
Gain 
Handset volume adjustment. RX is for receiving volume, TX is for 
transmission volume. Default values are 0dB for both parameters.  
Loudest volume: +6dB Lowest volume: -6dB. 
Call Progress/ Ring 
Tones 
Configure ring or tone frequencies according to preference. By default 
tones are set to North American frequencies. Frequencies should be 
configured with known values to avoid uncomfortable high pitch sounds. 










