am 968735e5: Merge "Fixing the NPE in SipPhone bug id: http://b/2987816" into gingerbread

Merge commit '968735e580b7728c6a17aff9b7356f9d74dc6eb3' into gingerbread-plus-aosp

* commit '968735e580b7728c6a17aff9b7356f9d74dc6eb3':
  Fixing the NPE in SipPhone
diff --git a/telephony/java/com/android/internal/telephony/sip/SipPhone.java b/telephony/java/com/android/internal/telephony/sip/SipPhone.java
index b009786..5af32da 100755
--- a/telephony/java/com/android/internal/telephony/sip/SipPhone.java
+++ b/telephony/java/com/android/internal/telephony/sip/SipPhone.java
@@ -754,7 +754,7 @@
                 Log.v(LOG_TAG, "hangup conn: " + mPeer.getUriString() + ": "
                         + ": on phone " + getPhone().getPhoneName());
                 try {
-                    mSipAudioCall.endCall();
+                    if (mSipAudioCall != null) mSipAudioCall.endCall();
                     setState(Call.State.DISCONNECTING);
                     setDisconnectCause(DisconnectCause.LOCAL);
                 } catch (SipException e) {