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• Generating or Detecting DTMF Tones Using a Voice Resource
4.16.1 Specifying DTMF Support
The Dialogic
®
Global Call API can be used to configure which DTMF transmission modes are
supported by the application. The DTMF mode can be specified in one of three ways:
• for all line devices simultaneously by using gc_SetConfigData( )
• on a per-line device basis by using gc_SetUserInfo( ) with a duration parameter value of
GC_ALLCALLS
• on a per-call basis by using gc_SetUserInfo( ) with a duration parameter value of
GC_SINGLECALL
The GC_PARM_BLK associated with the gc_SetConfigData( ) or gc_SetUserInfo( ) function is
used to indicate which DTMF modes are supported. The GC_PARM_BLK should include the
following parameter element
IPSET_DTMF
IPPARM_SUPPORT_DTMF_BITMASK
• value = a single bitmask value or the OR of more than one value to specify multiple
supported DTMF transmission modes
The IPPARM_SUPPORT_DTMF_BITMASK parameter can only be replaced rather than
modified. For each gc_SetConfigData( ) or gc_SetUserInfo( ) call, the previous value of the
IPPARM_SUPPORT_DTMF_BITMASK parameter is overwritten.
Bitmask values for SIP
SIP applications must set the DTMF signaling mode before calling gc_MakeCall( ),
gc_AnswerCall( ), gc_AcceptCall( ), or gc_CallAck( ). If a SIP application does not do this, the
function call fails with an IPERR_NO_DTMF_CAPABILITY indication. Supported bitmask
values are:
IP_DTMF_TYPE_INBAND_RTP
DTMF digits are sent and received inband via standard RTP transcoding.
Inband mode cannot be used when using low bit-rate (LBR) coders.
IP_DTMF_TYPE_RFC_2833
DTMF digits are sent and received in the RTP stream as defined in RFC 2833.
Bitmask values for H.323
An H.323 application that supports only the default H.245 User Input Indication (UII)
Alphanumeric mode does not need to explicitly set the DTMF signaling mode. All other
applications must set the DTMF mode using the following bitmask values:
IP_DTMF_TYPE_ALPHANUMERIC (default)
DTMF digits are sent and received in H.245 UII Alphanumeric messages.
HMP only supports the H.245 UII Alphanumeric mode; H.245 UII Signal mode is
not supported.