From 01a5ac22260f13d3c9ad6360a008192225ce4ace Mon Sep 17 00:00:00 2001
From: Hall Liu <hallliu@google.com>
Date: Wed, 11 Dec 2019 17:39:02 -0800
Subject: Enable RTT in the IMS stack when there's no SIM

When there's no SIM card, tell the IMS stack to enable RTT so that
emergency calls can still use RTT.

Bug: 122250491
Test: manual
Change-Id: I7d3753e20646fd32bb06570f06475b497cd5ebe3
---
 src/java/com/android/ims/ImsManager.java | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/java/com/android/ims/ImsManager.java b/src/java/com/android/ims/ImsManager.java
index 454429fe..8342c7ef 100644
--- a/src/java/com/android/ims/ImsManager.java
+++ b/src/java/com/android/ims/ImsManager.java
@@ -2048,8 +2048,14 @@ public class ImsManager implements IFeatureConnector {
     }
 
     public boolean updateRttConfigValue() {
+        // If there's no active sub anywhere on the device, enable RTT on the modem so that
+        // the device can make an emergency call.
+
+        boolean isActiveSubscriptionPresent = isActiveSubscriptionPresent();
         boolean isCarrierSupported =
-                getBooleanCarrierConfig(CarrierConfigManager.KEY_RTT_SUPPORTED_BOOL);
+                getBooleanCarrierConfig(CarrierConfigManager.KEY_RTT_SUPPORTED_BOOL)
+                || !isActiveSubscriptionPresent;
+
         boolean isRttUiSettingEnabled = Settings.Secure.getInt(mContext.getContentResolver(),
                 Settings.Secure.RTT_CALLING_MODE, 0) != 0;
         boolean isRttAlwaysOnCarrierConfig = getBooleanCarrierConfig(
@@ -2057,7 +2063,8 @@ public class ImsManager implements IFeatureConnector {
 
         boolean shouldImsRttBeOn = isRttUiSettingEnabled || isRttAlwaysOnCarrierConfig;
         logi("update RTT: settings value: " + isRttUiSettingEnabled + " always-on carrierconfig: "
-                + isRttAlwaysOnCarrierConfig);
+                + isRttAlwaysOnCarrierConfig
+                + "isActiveSubscriptionPresent: " + isActiveSubscriptionPresent);
 
         if (isCarrierSupported) {
             setRttConfig(shouldImsRttBeOn);
@@ -2723,6 +2730,12 @@ public class ImsManager implements IFeatureConnector {
                 subId != SubscriptionManager.DEFAULT_SUBSCRIPTION_ID;
     }
 
+    private boolean isActiveSubscriptionPresent() {
+        SubscriptionManager sm = (SubscriptionManager) mContext.getSystemService(
+                Context.TELEPHONY_SUBSCRIPTION_SERVICE);
+        return sm.getActiveSubscriptionIdList().length > 0;
+    }
+
     private void updateImsCarrierConfigs(PersistableBundle configs) throws ImsException {
         checkAndThrowExceptionIfServiceUnavailable();
 
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