Exhibit 21.1

SUBSIDIARIES

The full corporate name, jurisdiction of incorporation and registered and
beneficial ownership of the issued and outstanding shares of each direct and indirect Subsidiary is as follows:



|                                    |  |                 |  |                                                                                                                                                     
|----------------------------------- |  | --------------- |  | ----------------------------------------------------------------------------------------------------------------------------------------------------
|                                    |  | Jurisdiction of |  |                                                                                                                                                     
|Name of Subsidiary                  |  | Incorporation   |  | Ownership of Securities                                                                                                                             
|                                    |  |                
|Mitel Networks Holdings Limited     |  | United Kingdom  |  | Wholly-owned by the Corporation                                                                                                                     
|                                    |  |                
|Mitel Networks Asia Pacific Limited |  | Hong Kong       |  | Wholly-owned by the Corporation                                                                                                                     
|                                    |  |                
|Mitel Networks Limited              |  | United Kingdom  |  | Wholly-owned by Mitel Networks Holdings Limited, which is in turn wholly-owned by the Corporation                                                   
|                                    |  |                
|Mitel Networks, Inc.                |  | Delaware        |  | Wholly-owned by Mitel (Delaware), Inc., which is in turn wholly-owned by Mitel US Holdings, Inc. which is in turn wholly-owned by the Corporation   
|                                    |  |                
|Mitel U.S. Holdings, Inc.           |  | Delaware        |  | Wholly-owned by the Corporation                                                                                                                     
|                                    |  |                
|Mitel (Delaware), Inc.              |  | Delaware        |  | Wholly-owned by Mitel U.S. Holdings, Inc., which is in turn wholly-owned by the Corporation                                                         
|                                    |  |                
|Mitel Netsolutions, Inc.            |  | Texas           |  | Wholly-owned by Mitel (Delaware), Inc., which is in turn wholly-owned by Mitel U.S. Holdings, Inc., which is in turn wholly-owned by the Corporation
|                                    |  |                
|Mitel Leasing, Inc.                 |  | Arizona         |  | Wholly-owned by Mitel (Delaware), Inc., which is in turn wholly-owned by Mitel U.S. Holdings, Inc., which is in turn wholly-owned by the Corporation
|                                    |  |                
|Mitel Business Systems, Inc.        |  | Arizona         |  | Wholly-owned by Mitel (Delaware), Inc., which is in turn wholly-owned by Mitel U.S. Holdings, Inc., which is in turn wholly-owned by the
Corporation



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|                                      |  |                     |  |                                                                                                                                                                                                            
|------------------------------------- |  | ------------------- |  | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|                                      |  |                    
|Mitel Technologies, Inc.              |  | Arizona             |  | Wholly-owned by Mitel (Delaware), Inc., which is in turn wholly-owned by Mitel U.S. Holdings, Inc., which is in turn wholly-owned by the Corporation                                                       
|                                      |  |                    
|Inter-Tel Lake Limited                |  | Republic of Ireland |  | Wholly-owned by Mitel (Delaware), Inc., which is in turn wholly-owned by Mitel U.S. Holdings, Inc., which is in turn wholly-owned by the Corporation                                                       
|                                      |  |                    
|Swan Solutions Limited                |  | United Kingdom      |  | Wholly-owned by Mitel Networks, Inc., which is in turn wholly-owned by Mitel (Delaware), Inc., which is in turn wholly-owned by Mitel U.S. Holdings, Inc., which is in turn
wholly-owned by the Corporation
|                                      |  |                    
|Lake Communications Limited           |  | Republic of Ireland |  | Wholly-owned by Inter-Tel Lake Limited, which is in turn wholly-owned by Mitel (Delaware), Inc., which is in turn wholly-owned by Mitel US Holdings, Inc., which is in turn
wholly-owned by the Corporation
|                                      |  |                    
|Lake Electronics Technologies Limited |  | Republic of Ireland |  | Wholly-owned by Inter-Tel Lake Limited, which is in turn wholly-owned by Mitel (Delaware), Inc., which is in turn wholly-owned by Mitel US Holdings, Inc., which is in turn
wholly-owned by the Corporation