diff --git a/include/commissioning/commissioner.h b/include/commissioning/commissioner.h
index 42f809819..68112191a 100644
--- a/include/commissioning/commissioner.h
+++ b/include/commissioning/commissioner.h
@@ -212,6 +212,16 @@ OTAPI ThreadError OTCALL otSendMgmtCommissionerGet(otInstance *, const uint8_t *
 OTAPI ThreadError OTCALL otSendMgmtCommissionerSet(otInstance *, const otCommissioningDataset *aDataset,
                                                    const uint8_t *aTlvs, uint8_t aLength);
 
+/**
+ * This function returns the origian Commissioner Session ID.
+ *
+ * @param[in]  aInstance  A pointer to an OpenThread instance.
+ *
+ * @returns The current commissioner session id.
+ *
+ */
+OTAPI uint16_t OTCALL otCommissionerGetSessionId(otInstance *);
+
 /**
  * @}
  *
diff --git a/src/cli/README.md b/src/cli/README.md
index be9c26181..085dc4caa 100644
--- a/src/cli/README.md
+++ b/src/cli/README.md
@@ -307,6 +307,16 @@ Done
 Conflict: dead, 00000800
 ```
 
+### commissioner sessionid
+
+Get current commissioner session id.
+
+```bash
+> commissioner sessionid
+0
+Done
+```
+
 ### contextreusedelay
 
 Get the CONTEXT_ID_REUSE_DELAY value.
diff --git a/src/cli/cli.cpp b/src/cli/cli.cpp
index 860efc091..efbba8ec3 100644
--- a/src/cli/cli.cpp
+++ b/src/cli/cli.cpp
@@ -2375,6 +2375,10 @@ void Interpreter::ProcessCommissioner(int argc, char *argv[])
 
         SuccessOrExit(error = otSendMgmtCommissionerSet(mInstance, &dataset, tlvs, static_cast<uint8_t>(length)));
     }
+    else if (strcmp(argv[0], "sessionid") == 0)
+    {
+        sServer->OutputFormat("%d\r\n", otCommissionerGetSessionId(mInstance));
+    }
 
 exit:
     AppendResult(error);
diff --git a/src/core/openthread.cpp b/src/core/openthread.cpp
index a3ec6d818..bfee71b61 100644
--- a/src/core/openthread.cpp
+++ b/src/core/openthread.cpp
@@ -1669,6 +1669,11 @@ ThreadError otSendMgmtCommissionerSet(otInstance *aInstance, const otCommissioni
 {
     return aInstance->mThreadNetif.GetCommissioner().SendMgmtCommissionerSetRequest(*aDataset, aTlvs, aLength);
 }
+
+uint16_t otCommissionerGetSessionId(otInstance *aInstance)
+{
+    return aInstance->mThreadNetif.GetCommissioner().GetSessionId();
+}
 #endif  // OPENTHREAD_ENABLE_COMMISSIONER
 
 #if OPENTHREAD_ENABLE_JOINER
diff --git a/tools/harness-thci/ARM.py b/tools/harness-thci/ARM.py
index 1028712c5..5f6653275 100644
--- a/tools/harness-thci/ARM.py
+++ b/tools/harness-thci/ARM.py
@@ -56,6 +56,7 @@ class ARM(IThci):
     isPowerDown = False              # indicate if Thread device experiences a power down event
     isWhiteListEnabled = False       # indicate if Thread device enables white list filter
     isBlackListEnabled = False       # indicate if Thread device enables black list filter
+    isActiveCommissioner = False     # indicate if Thread device is an active commissioner
     LOWEST_POSSIBLE_PARTATION_ID = 0x1
 
     #def __init__(self, SerialPort=COMPortName, EUI=MAC_Address):
@@ -652,6 +653,11 @@ class ARM(IThci):
         except Exception, e:
             ModuleHelper.WriteIntoDebugLogger("setKeySwitchGuardTime() Error; " + str(e))
 
+    def __getCommissionerSessionId(self):
+        """ get the commissioner session id allocated from Leader """
+        print '%s call getCommissionerSessionId' % self.port
+        return self.__sendCommand('commissioner sessionid')[0]
+
     def _connect(self):
         print 'My port is %s' % self.port
         if self.port.startswith('COM'):
@@ -1239,6 +1245,7 @@ class ARM(IThci):
             self.setNetworkKey(self.networkKey)
             self.isWhiteListEnabled = False
             self.isBlackListEnabled = False
+            self.isActiveCommissioner = False
             self.firmware = 'Nov 4 2016 07:24:59'
         except Exception, e:
             ModuleHelper.WriteIntoDebugLogger("setDefaultValue() Error: " + str(e))
@@ -1893,6 +1900,7 @@ class ARM(IThci):
             cmd = 'commissioner start'
             print cmd
             if self.__sendCommand(cmd)[0] == 'Done':
+                self.isActiveCommissioner = True
                 time.sleep(20) # time for petition process
                 return True
         return False
@@ -1955,6 +1963,7 @@ class ARM(IThci):
             cmd = 'commissioner start'
             print cmd
             if self.__sendCommand(cmd)[0] == 'Done':
+                self.isActiveCommissioner = True
                 time.sleep(40) # time for petition process and at least one keep alive
                 return True
             else:
@@ -2381,8 +2390,16 @@ class ARM(IThci):
             cmd = 'commissioner mgmtset'
 
             if xCommissionerSessionID != None:
+                # use assigned session id
                 cmd += ' sessionid '
                 cmd += str(xCommissionerSessionID)
+            elif xCommissionerSessionID == None:
+                # use original session id
+                if self.isActiveCommissioner == True:
+                    cmd += ' sessionid '
+                    cmd += self.__getCommissionerSessionId()
+                else:
+                    pass
 
             if xSteeringData != None:
                 cmd += ' steeringdata '
@@ -2392,6 +2409,10 @@ class ARM(IThci):
                 cmd += ' locator '
                 cmd += str(xBorderRouterLocator)
 
+            if xChannelTlv != None:
+                cmd += ' binary '
+                cmd += '000300' + hex(xChannelTlv).lstrip('0x').zfill(4) 
+
             print cmd
 
             return self.__sendCommand(cmd)[0] == 'Done'