Trendnet TVP-224HR User Manual

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TVP-224HR User’s Guide 
64 
tone to the PSTN. This method in which the TVP-224HR handles DTMF tone is 
so called DTMF relay. 
The TVP-224HR handles DTMF relay per H.323 specifications. Certain third 
party VoIP devices may handle DTMF relay per IMTC standard. For the TVP-
224HR to interoperate with those VoIP devices, users need to specify which 
remote VoIP devices uses IMTC conforming DTMF relay technique. Refer to CLI 
command Error! Reference source not found. on Chapter 8 for detailed 
information on how to select DTMF relay mode. 
8.7 Voice 
Codecs 
Voice codecs supported by the TVP-224HR include G.711, G.723.1 5.3kbps, 
G.723.1 6.3kbps and G.729 AB. When setting up a call, two VoIP Gateways 
automatically negotiate with each other until an agreement on codec is 
determined.