Dtmf Methods; Preferred Vocoder (Codec) - Grandstream Networks HT502 User Manual

Server. The following three (3) settings are useful in the STUN Server scenario:
1. STUN Server (under Advanced Settings webpage)
Enter a STUN Server IP (or FQDN) that you may have, or look up a free public STUN Server on the
internet and enter it on this field. If using Public IP, keep this field blank.
2. Use Random Ports (under Advanced Settings webpage)
This setting depends on your network settings. Generally, if you have multiple IP devices under the
same network, it should be set to Yes. If using a Public IP address, set this parameter to No.
3. NAT Traversal (under the Profile web pages)
Set this to Yes when gateway is behind firewall on a private network.

DTMF Methods

DTMF Settings are in FXS portX pages.

DTMF in-audio

DTMF via RTP (RFC2833)

DTMF via SIP INFO
Set priority of DTMF methods according to your preference. This setting should be based on your server
DTMF setting.

Preferred VOCODER (Codec)

The HT502 supports a broad range of voice codecs. Under Profile web pages, choose your preferred
order of different codecs:

PCMU/A (or G711µ/a)

G729 A/B/E

G723

G726 (16/24/32/40)

iLBC
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