User`s manual

MP-1xx H.323 User’s Manual 8. Gateway Capabilities Description
Version 4.4 153 March 2005
(once); if not defined, each endpoint registers twice, in E.164 format and H.323-ID format
(using the ‘H.323 Port ID’ table or, if this table isn’t defined, as a string).
 NPI/TON from Table [3] = N/A in this mode.
 NPI/TON and H323-ID [4] = N/A in this mode.
For detailed information on the ‘H.323 Port ID’ table refer to Section
5.8.8.1 on page 92.
8.3 Configuring the DTMF Transport Types
The MP-1xx H.323 gateway supports several methods of conveying DTMF digits over the IP
network. Three methods are controlled by H.245 protocol and therefore use its capability
exchange mechanism to ensure coordination with the remote side. A fourth method uses Q.931
Info messages. If neither of these methods is selected, DTMF is transferred inside the audio
stream.
The MP-1xx gateway supports the following DTMF transfer methods (the first three methods use
H.245 capability exchange):
1. RFC 2833 - DTMF digits are relayed to the remote side as part of the RTP stream according
to the RFC 2833 standard. The H.245 capability exchange coordinates the source and
destination payload types. The gateway’s received packets’ RFC 2833 payload type is
configured by the parameter RFC2833PayloadType (default 96); the gateway’s transmitted
payload type is identical to the payload type received from the remote party.
2. H.245 Signal – Out-of-Band DTMF using H.245 UserInfo messages (refer to the note below).
3. H.245 User Input - Out-of-Band DTMF, similar to H.245 Signal, but without DTMF length
reconstruction (refer to the note below).
4. Q.931 Info Message – (without H.245 negotiation): Similar to H.245 User Input but over
Q.931. This method is not included in the H.245 capabilities exchange and therefore, when
selected, is always used.
The gateway’s DTMF transfer mechanism ensures that only a single DTMF digit is generated.
The mechanism erases all digits from the audio stream. This solves the problem of double
detection (caused as a result of different paths of DTMF) at the remote side.
5. If none of the above transfer methods is used, DTMF digits can be sent as part of the audio
stream (in RTP packets). This is normally used with G.711 coders (with other LBR coders,
the quality of the DTMF digits is reduced). Set the parameter DTMFTransportType to
"Transparent" for DTMF to not be removed from the voice stream.
Note: When using Fast Start the H.245 channel remains close, and out-of-band
signaling can’t be used, unless “OpenH245onFS” is set to 1 or remote
gateway/terminal opens the H.245 channel.
 To configure the MP-1xx DTMF transfer type, take these 3 steps:
1. Set the preferred Transmit DTMF methods using the TxDTMFOption table. Note that DTMF
negotiation methods are prioritized according to the order of their appearance.
2. Set the supported Receive DTMF negotiation method using
RxDTMFOption parameter.
3. If needed, Set the supported hook-flash (receive and transmit) Transport Type method, using
the HookFlashOption parameter.
 To configure the MP-1xx to convey DTMF digits in the audio stream,
take these 2 steps:
1. Ensure that neither of the following parameters is configured (set to 'not supported'):
DTMFTxOptions, DTMFRxOption and HookFlashOption. Also ensure that neither of the
obsolete parameters: Is931MsgUsed and IsHookFlashUsed is configured (set to 'No').