Add carrier config key for TTY support.

Add carrier config key to determine if a carrier supports TTY.

Bug: 116764319
Test: Manual; turned off key and observed settings doesn't show TTY.
Test: Manual; turned on key (default) and observed settings does show TTY.
Change-Id: I9dff154740213ff9627c0cc07452f0b22b59e8f6

2 files changed, 15 insertions, 0 deletions

diff --git a/api/current.txt b/api/current.txt
index 5084fda7459c..65d725b899b4 100755
--- a/api/current.txt
+++ b/api/current.txt
@@ -42269,6 +42269,7 @@ package android.telephony {
     field public static final String KEY_SUPPORT_PAUSE_IMS_VIDEO_CALLS_BOOL = "support_pause_ims_video_calls_bool";
     field public static final String KEY_SUPPORT_SWAP_AFTER_MERGE_BOOL = "support_swap_after_merge_bool";
     field public static final String KEY_TREAT_DOWNGRADED_VIDEO_CALLS_AS_VIDEO_CALLS_BOOL = "treat_downgraded_video_calls_as_video_calls_bool";
+    field public static final String KEY_TTY_SUPPORTED_BOOL = "tty_supported_bool";
     field public static final String KEY_USE_HFA_FOR_PROVISIONING_BOOL = "use_hfa_for_provisioning_bool";
     field public static final String KEY_USE_OTASP_FOR_PROVISIONING_BOOL = "use_otasp_for_provisioning_bool";
     field public static final String KEY_USE_RCS_PRESENCE_BOOL = "use_rcs_presence_bool";
diff --git a/telephony/java/android/telephony/CarrierConfigManager.java b/telephony/java/android/telephony/CarrierConfigManager.java
index aef3dbf5ff26..368a37101f94 100644
--- a/telephony/java/android/telephony/CarrierConfigManager.java
+++ b/telephony/java/android/telephony/CarrierConfigManager.java
@@ -31,6 +31,7 @@ import android.os.PersistableBundle;
 import android.os.RemoteException;
 import android.os.ServiceManager;
 import android.service.carrier.CarrierService;
+import android.telecom.TelecomManager;
 import android.telephony.ims.ImsReasonInfo;
 
 import com.android.internal.telephony.ICarrierConfigLoader;
@@ -2110,6 +2111,18 @@ public class CarrierConfigManager {
     public static final String KEY_RTT_SUPPORTED_BOOL = "rtt_supported_bool";
 
     /**
+     * Boolean flag indicating whether the carrier supports TTY.
+     * <p>
+     * Note that {@link #KEY_CARRIER_VOLTE_TTY_SUPPORTED_BOOL} controls availability of TTY over
+     * VoLTE; if {@link #KEY_TTY_SUPPORTED_BOOL} is disabled, then
+     * {@link #KEY_CARRIER_VOLTE_TTY_SUPPORTED_BOOL} is also implicitly disabled.
+     * <p>
+     * {@link TelecomManager#isTtySupported()} should be used to determine if a device supports TTY,
+     * and this carrier config key should be used to see if the current carrier supports it.
+     */
+    public static final String KEY_TTY_SUPPORTED_BOOL = "tty_supported_bool";
+
+    /**
      * Indicates if the carrier supports auto-upgrading a call to RTT when receiving a call from a
      * RTT-supported device.
      * @hide
@@ -2749,6 +2762,7 @@ public class CarrierConfigManager {
         sDefaults.putStringArray(KEY_ROAMING_OPERATOR_STRING_ARRAY, null);
         sDefaults.putBoolean(KEY_SHOW_IMS_REGISTRATION_STATUS_BOOL, false);
         sDefaults.putBoolean(KEY_RTT_SUPPORTED_BOOL, false);
+        sDefaults.putBoolean(KEY_TTY_SUPPORTED_BOOL, true);
         sDefaults.putBoolean(KEY_DISABLE_CHARGE_INDICATION_BOOL, false);
         sDefaults.putBoolean(KEY_SUPPORT_NO_REPLY_TIMER_FOR_CFNRY_BOOL, true);
         sDefaults.putStringArray(KEY_FEATURE_ACCESS_CODES_STRING_ARRAY, null);