Call Control
3-58 G24-L AT Commands Reference Manual April 15, 2008
The following table shows the +MTTY parameters.
Notes:
VCO: Voice Carry Over is intended for people who cannot hear but are able to speak
clearly. During a VCO relay call, the Deaf or Hard-of-Hearing caller speaks directly to
the person they are conversing with. When that person responds, a Communication
Assistant (CA) will type back exactly what is said and it will appear on the screen of your
TTY or VCO phone.
HCO: Hearing Carry Over allows Speech Disabled callers who can hear well on the
telephone to listen directly to the person they are talking with. The Speech Disabled Relay
user types his or her part of the conversation on a TTY. A Communication Assistant (CA)
then speaks the typed conversation, word for word, to the standard telephone user.
Command
Type Syntax Response/Action Remarks
Set
AT+MTTY=<n> OK
or:
+CME ERROR: <err>
The SET command is used for setting
the current TTY mode.
Read
AT+MTTY? + MTTY : <n>
OK
or:
+CME ERROR: <err>
The READ command returns the
current TTY mode <n>.
Test
AT+MTTY=? +MTTY : (0-3)
OK
or:
+CME ERROR: <err>
The Test command returns the possible
value’s range.
Table 3-32: +MTTY Parameters
<Parameter> Description
<n> 0 Normal voice mode.
1 Full TTY mode (both uplink and downlink support TTY data; used when both
side parties are deaf).
2 VCO mode (Voice Carry Over- uplink is voice active downlink is TTY).
3 HCO mode (Hearing Carry Over-downlink is voice active uplink is TTY).
The default value:
• On Power Up - as previously saved in FLEX bytes.
• Before set command is first used, mode is set to Normal voice mode.
