Add carrier config variable to hide merge call button

Bug: 22864941
Change-Id: Ief5f8078e53a46cc9bf7627729dba7e28270a231
diff --git a/telephony/java/android/telephony/CarrierConfigManager.java b/telephony/java/android/telephony/CarrierConfigManager.java
index 3054422..9dc94c8 100644
--- a/telephony/java/android/telephony/CarrierConfigManager.java
+++ b/telephony/java/android/telephony/CarrierConfigManager.java
@@ -350,6 +350,13 @@
     public static final String KEY_IMS_DTMF_TONE_DELAY_INT = "ims_dtmf_tone_delay_int";
 
     /**
+     * Determines whether conference calls are supported by a carrier.  When {@code true},
+     * conference calling is supported, {@code false otherwise}.
+     * @hide
+     */
+    public static final String KEY_SUPPORT_CONFERENCE_CALL_BOOL = "support_conference_call_bool";
+
+    /**
      * If this is true, the SIM card (through Customer Service Profile EF file) will be able to
      * prevent manual operator selection. If false, this SIM setting will be ignored and manual
      * operator selection will always be available. See CPHS4_2.WW6, CPHS B.4.7.1 for more
@@ -448,6 +455,7 @@
         sDefaults.putStringArray(KEY_CDMA_NONROAMING_NETWORKS_STRING_ARRAY, null);
         sDefaults.putBoolean(KEY_FORCE_HOME_NETWORK_BOOL, false);
         sDefaults.putInt(KEY_IMS_DTMF_TONE_DELAY_INT, 0);
+        sDefaults.putBoolean(KEY_SUPPORT_CONFERENCE_CALL_BOOL, true);
 
         // MMS defaults
         sDefaults.putBoolean(KEY_MMS_ALIAS_ENABLED_BOOL, false);