--- a/dom/system/gonk/ril_worker.js
+++ b/dom/system/gonk/ril_worker.js
@@ -1975,24 +1975,32 @@ RilObject.prototype = {
       this.hangUpForeground(options);
     } else {
       this.hangUpBackground(options);
     }
   },
 
   holdConference: function(options) {
     if (this._isCdma) {
+      // We cannot hold a conference call on CDMA.
+      options.success = false;
+      options.errorMsg = GECKO_ERROR_GENERIC_FAILURE;
+      this.sendChromeMessage(options);
       return;
     }
 
     this.switchActiveCall(options);
   },
 
   resumeConference: function(options) {
     if (this._isCdma) {
+      // We cannot resume a conference call on CDMA
+      options.success = false;
+      options.errorMsg = GECKO_ERROR_GENERIC_FAILURE;
+      this.sendChromeMessage(options);
       return;
     }
 
     this.switchActiveCall(options);
   },
 
   /**
    * Get current calls.