--- a/dom/telephony/TelephonyCallInfo.cpp
+++ b/dom/telephony/TelephonyCallInfo.cpp
@@ -10,38 +10,32 @@ namespace mozilla {
 namespace dom {
 namespace telephony {
 
 NS_IMPL_ISUPPORTS(TelephonyCallInfo, nsITelephonyCallInfo)
 
 TelephonyCallInfo::TelephonyCallInfo(uint32_t aClientId,
                                      uint32_t aCallIndex,
                                      uint16_t aCallState,
-                                     const nsAString& aDisconnectedReason,
-
                                      const nsAString& aNumber,
                                      uint16_t aNumberPresentation,
                                      const nsAString& aName,
                                      uint16_t aNamePresentation,
-
                                      bool aIsOutgoing,
                                      bool aIsEmergency,
                                      bool aIsConference,
                                      bool aIsSwitchable,
                                      bool aIsMergeable)
   : mClientId(aClientId),
     mCallIndex(aCallIndex),
     mCallState(aCallState),
-    mDisconnectedReason(aDisconnectedReason),
-
     mNumber(aNumber),
     mNumberPresentation(aNumberPresentation),
     mName(aName),
     mNamePresentation(aNamePresentation),
-
     mIsOutgoing(aIsOutgoing),
     mIsEmergency(aIsEmergency),
     mIsConference(aIsConference),
     mIsSwitchable(aIsSwitchable),
     mIsMergeable(aIsMergeable)
 {
 }
 
@@ -62,23 +56,16 @@ TelephonyCallInfo::GetCallIndex(uint32_t
 NS_IMETHODIMP
 TelephonyCallInfo::GetCallState(uint16_t* aCallState)
 {
   *aCallState = mCallState;
   return NS_OK;
 }
 
 NS_IMETHODIMP
-TelephonyCallInfo::GetDisconnectedReason(nsAString& aDisconnectedReason)
-{
-  aDisconnectedReason = mDisconnectedReason;
-  return NS_OK;
-}
-
-NS_IMETHODIMP
 TelephonyCallInfo::GetNumber(nsAString& aNumber)
 {
   aNumber = mNumber;
   return NS_OK;
 }
 
 NS_IMETHODIMP
 TelephonyCallInfo::GetNumberPresentation(uint16_t* aNumberPresentation)

--- a/dom/telephony/TelephonyCallInfo.h
+++ b/dom/telephony/TelephonyCallInfo.h
@@ -16,48 +16,36 @@ namespace dom {
 namespace telephony {
 
 class TelephonyCallInfo final : public nsITelephonyCallInfo
 {
 public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSITELEPHONYCALLINFO
 
-  TelephonyCallInfo(uint32_t aClientId,
-                    uint32_t aCallIndex,
-                    uint16_t aCallState,
-                    const nsAString& aDisconnectedReason,
-
-                    const nsAString& aNumber,
-                    uint16_t aNumberPresentation,
-                    const nsAString& aName,
-                    uint16_t aNamePresentation,
-
-                    bool aIsOutgoing,
-                    bool aIsEmergency,
-                    bool aIsConference,
-                    bool aIsSwitchable,
-                    bool aIsMergeable);
+  TelephonyCallInfo(uint32_t aClientId, uint32_t aCallIndex,
+                    uint16_t aCallState, const nsAString& aNumber,
+                    uint16_t aNumberPresentation, const nsAString& aName,
+                    uint16_t aNamePresentation, bool aIsOutgoing,
+                    bool aIsEmergency, bool aIsConference,
+                    bool aIsSwitchable, bool aIsMergeable);
 
 private:
   // Don't try to use the default constructor.
   TelephonyCallInfo() {}
 
   ~TelephonyCallInfo() {}
 
   uint32_t mClientId;
   uint32_t mCallIndex;
   uint16_t mCallState;
-  nsString mDisconnectedReason;
-
   nsString mNumber;
   uint16_t mNumberPresentation;
   nsString mName;
   uint16_t mNamePresentation;
-
   bool mIsOutgoing;
   bool mIsEmergency;
   bool mIsConference;
   bool mIsSwitchable;
   bool mIsMergeable;
 };
 
 } // namespace telephony

--- a/dom/telephony/gonk/TelephonyService.js
+++ b/dom/telephony/gonk/TelephonyService.js
@@ -125,23 +125,20 @@ MobileCallForwardingOptions.prototype = 
   timeSeconds: -1,
   serviceClass: nsIMobileConnection.ICC_SERVICE_CLASS_NONE
 };
 
 function TelephonyCallInfo(aCall) {
   this.clientId = aCall.clientId;
   this.callIndex = aCall.callIndex;
   this.callState = aCall.state;
-  this.disconnectedReason = aCall.disconnectedReason || "";
-
   this.number = aCall.number;
   this.numberPresentation = aCall.numberPresentation;
   this.name = aCall.name;
   this.namePresentation = aCall.namePresentation;
-
   this.isOutgoing = aCall.isOutgoing;
   this.isEmergency = aCall.isEmergency;
   this.isConference = aCall.isConference;
   this.isSwitchable = aCall.isSwitchable;
   this.isMergeable = aCall.isMergeable;
 }
 TelephonyCallInfo.prototype = {
   QueryInterface: XPCOMUtils.generateQI([Ci.nsITelephonyCallInfo]),
@@ -152,23 +149,20 @@ TelephonyCallInfo.prototype = {
     interfaces:       [Ci.nsITelephonyCallInfo]
   }),
 
   // nsITelephonyCallInfo
 
   clientId: 0,
   callIndex: 0,
   callState: nsITelephonyService.CALL_STATE_UNKNOWN,
-  disconnectedReason: "",
-
   number: "",
   numberPresentation: nsITelephonyService.CALL_PRESENTATION_ALLOWED,
   name: "",
   namePresentation: nsITelephonyService.CALL_PRESENTATION_ALLOWED,
-
   isOutgoing: true,
   isEmergency: false,
   isConference: false,
   isSwitchable: true,
   isMergeable: true
 };
 
 function Call(aClientId, aCallIndex) {

--- a/dom/telephony/ipc/TelephonyIPCSerializer.h
+++ b/dom/telephony/ipc/TelephonyIPCSerializer.h
@@ -85,64 +85,47 @@ struct ParamTraits<nsITelephonyCallInfo*
     if (isNull) {
       *aResult = nullptr;
       return true;
     }
 
     uint32_t clientId;
     uint32_t callIndex;
     uint16_t callState;
-    nsString disconnectedReason;
-
     nsString number;
     uint16_t numberPresentation;
     nsString name;
     uint16_t namePresentation;
-
     bool isOutgoing;
     bool isEmergency;
     bool isConference;
     bool isSwitchable;
     bool isMergeable;
 
     // It's not important to us where it fails, but rather if it fails
     if (!(ReadParam(aMsg, aIter, &clientId) &&
           ReadParam(aMsg, aIter, &callIndex) &&
           ReadParam(aMsg, aIter, &callState) &&
-          ReadParam(aMsg, aIter, &disconnectedReason) &&
-
           ReadParam(aMsg, aIter, &number) &&
           ReadParam(aMsg, aIter, &numberPresentation) &&
           ReadParam(aMsg, aIter, &name) &&
           ReadParam(aMsg, aIter, &namePresentation) &&
-
           ReadParam(aMsg, aIter, &isOutgoing) &&
           ReadParam(aMsg, aIter, &isEmergency) &&
           ReadParam(aMsg, aIter, &isConference) &&
           ReadParam(aMsg, aIter, &isSwitchable) &&
           ReadParam(aMsg, aIter, &isMergeable))) {
       return false;
     }
 
     nsCOMPtr<nsITelephonyCallInfo> info =
-        new TelephonyCallInfo(clientId,
-                              callIndex,
-                              callState,
-                              disconnectedReason,
-
-                              number,
-                              numberPresentation,
-                              name,
-                              namePresentation,
-
-                              isOutgoing,
-                              isEmergency,
-                              isConference,
-                              isSwitchable,
-                              isMergeable);
+        new TelephonyCallInfo(clientId, callIndex, callState, number,
+                              numberPresentation, name, namePresentation,
+                              isOutgoing, isEmergency, isConference,
+                              isSwitchable, isMergeable);
 
     info.forget(aResult);
 
     return true;
   }
 };
 
 

--- a/dom/telephony/nsITelephonyCallInfo.idl
+++ b/dom/telephony/nsITelephonyCallInfo.idl
@@ -1,15 +1,15 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "nsISupports.idl"
 
-[scriptable, uuid(e5e1be26-a3d4-49b3-8d9f-c1df5192b364)]
+[scriptable, uuid(3ea2d155-8ea2-42be-85d7-bd8ede8afc40)]
 interface nsITelephonyCallInfo : nsISupports
 {
   /**
    * Indicate the RIL client, 0 ~ (number of client - 1).
    */
   readonly attribute unsigned long clientId;
 
   /**
@@ -18,24 +18,16 @@ interface nsITelephonyCallInfo : nsISupp
   readonly attribute unsigned long callIndex;
 
   /**
    * One of the nsITelephonyService::CALL_STATE_* values.
    */
   readonly attribute unsigned short callState;
 
   /**
-   * The disconnectedReason of a call is defualt to an empty string when the
-   * call is "not disconnected", but once the call becomes "disconnected" the
-   * disconnectedReason should be a non-empty string no matter the call is
-   * disconnected for a noraml reason or an error.
-   */
-  readonly attribute DOMString disconnectedReason;
-
-  /**
    * Number of the other party.
    */
   readonly attribute DOMString number;
 
   /**
    * Presentation of the call number.
    * One of the nsITelephonyService::CALL_PRESENTATION_* values.
    */