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MC55 AT Command Set
16.16 AT^SNFTTY
16.16
AT^SNFTTY Switch audio path to TTY/CTM mode
MC55 offers basic support for equipment using the CTM standard (Cellular Text Telephone Modems). The ben-
efit of CTM is that text characters typed on a TTY device (Text Telephone Type-writer) can be transformed into
special audio burst signals for reliable transmission via the existing speech channels of a cellular phone system.
Designed to set the module's speech system into CTM mode, the
to be connected to one of the three audio interfaces of MC55. Traditional TTY devices that do not incorporate
CTM functionality can be connected through an external TTY-to-CTM adapter.
If in CTM mode, the ME will set the necessary bearer capability bit on outgoing (mobile originated) calls.
If a CTM call is received while the ME's audio path is set to normal speech mode, this call will be rejected because
CTM coded speech data could not be understood by a user.
Related documents: Refer to the relevant standards, such as 3GPP TS 26.226 (ETSI TS 126 226) and 3GPP
TS 23.228 (ETSI TS 123 226). 3GPP documentation can be retrieved, for example, from http://www.3gpp.org/
specs/specs.htm. In Application Note 22 "Using TTY / CTM equipment" you can find all the information you need
to connect TTY / CTM equipment to MC55, plus background information and general operating instructions.
Syntax
Test Command
AT^SNFTTY=?
Response(s)
^SNFTTY: (list of supported
OK
Read Command
AT^SNFTTY?
Response(s)
^SNFTTY:
<state>
OK
Write Command
AT^SNFTTY=<state>
Response(s)
OK
PIN
ASC0
ASC1
MUX1
!
%
%
Reference(s)
SIEMENS
MC55_ATC_V01.05
Confidential / Released
s)
<state>
MUX2
MUX3
%
%
%
Page 417 of 469
s
command allows a CTM device
AT^SNFTTY
m
obile
2/10/04
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