Grandstream Networks 386

HandyTone-386 User Manual Grandstream Networks, Inc.

NAT Traversal This parameter defines whether the HT386 NAT traversal mechanism will be

activated or not. If activated (by choosing “Yes”) and a STUN server is also

specified, then the HT386 will behave according to the STUN client

specification. Under this mode, the embedded STUN client inside the HT386

will attempt to detect if and what type of firewall/NAT it is sitting behind

through communication with the specified STUN server. If the detected NAT is

a Full Cone, Restricted Cone, or a Port-Restricted Cone, the HT386 will

attempt to 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 HT386 will p eriodically (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.

Preferred Vocoder The HT386 supports 6 different codec types including :

G.711 A/Ulaw G.723.1, G.726, G.729A/B, iLBC.

A user can configure codecs in a preference list that will be included with the

same preference order in SDP message.

Voice Frames per

TX This field contains the number of voice frames to be transmitted in a single

packet. When setting this value, the user should be aware of the requested

packet time (used in SDP message) as a result of confi guring this parameter.

This parameter is associated with the first codec in the above codec Preference

List or the actual used payload type negotiated between the 2 conversation

parties at run time.

e.g., if the first codec is configured as G723 and the “Voice Frames per TX” is

set to be 2, then the “ptime” value in the SDP message of an INVITE request

will be 60ms because each G723 voice frame contains 30ms of audio.

Similarly, if this field is set to be 2 and if the first codec chosen is G729 or

G711 or G726, then the “ptime” value in the SDP message of an INVITE

request will be 20ms.

If the configured voice frames per TX exceeds the maximum allowed value, the

HT386 will use and save the maximum allowed value for the corresponding

first codec choice. The maximum value for PCM is 10(x10ms) frames; for

G726, it is 20 (x10ms) frames; for G723, it is 32 (x30ms) frames; for

G729/G728, 64 (x10ms) and 64 (x2.5ms) frames respectively. Please be careful

when massage those parameters.

G723 Rate: Encoding rate for G723 codec. By default, 6.3kbps rate is set.

iLBC frame size: iLBC packet frame size. Default is 20ms. For Asterisk PBX, 30ms might need

to be set.

iLBC payload type: Payload type for iLBC. Default value is 97. The valid range is between 96 and

127.