Exhibit 2.3



SECOND SUPPLEMENTAL
INDENTURE



SECOND SUPPLEMENTAL INDENTURE(this “Supplemental
Indenture”), dated as of November 13, 2015, among Telesat (IOM) Holdings Limited (“Telesat IOM Holdings”)
and Telesat International Limited (“Telesat UK”, and together with Telesat IOM Holdings, the “Guaranteeing
Subsidiaries”), each a subsidiary of Telesat Canada (the “Issuer”), the Issuer, Telesat LLC, a Delaware
limited liability company (the “Co-Issuer” and together with the Issuer, the “Co-Issuers”),
the other Guarantors (as defined in the Indenture referred to herein (the “Existing Guarantors”)) and The Bank
of New York Mellon, as trustee under the Indenture referred to below (the “Trustee”).



WITNESSETH



WHEREAS, the Co-Issuers and the Existing
Guarantors have heretofore executed and delivered to the Trustee an indenture (as supplemented by the First Supplemental Indenture
thereto, dated September 13, 2013, the “Indenture”), dated as of May 14, 2012 providing for the issuance of
6.0% Senior Notes Due 2017 (the “Notes”);



WHEREAS, the Indenture provides that under
certain circumstances the Guaranteeing Subsidiaries shall execute and deliver to the Trustee a supplemental indenture pursuant
to which the Guaranteeing Subsidiaries shall unconditionally guarantee all of the Co-Issuers’ obligations under the Notes
and the Indenture (each, a “Guarantee”, and collectively, the “Guarantees”);



WHEREAS, pursuant to Section 901 of the
Indenture, the Trustee is authorized to execute and deliver this Supplemental Indenture;



WHEREAS, the Co-Issuers and Guarantors have
been authorized by Board Resolutions of their respective Board of Directors to enter into this Supplemental Indenture; and



WHEREAS, the Co-Issuers hereby direct the
Trustee to execute and deliver this Supplemental Indenture.



NOW, THEREFORE, in consideration of the
foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged, the Guaranteeing Subsidiaries
and the Trustee mutually covenant and agree for the equal and ratable benefit of the Holders of the Notes as follows:



1.          CAPITALIZED
TERMS. Capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture.



2.          GUARANTEE.
Each Guaranteeing Subsidiary hereby agrees to provide an unconditional Guarantee on the terms and subject to the conditions set
forth in the Indenture, including but not limited to Article Twelve thereof.



3.          WAIVER
OF BENEFIT OR ADVANTAGE. Each Guaranteeing Subsidiary hereby waives and will not in any manner whatsoever claim or take the benefit
or advantage of, any rights of reimbursement, indemnity or subrogation or any other rights against Holdings or any other Restricted
Subsidiary as a result of any payment by such Restricted Subsidiary under its Guarantee until all amounts then due and payable
by the Co-Issuers with respect to the Notes shall have been paid in full.











4.          NO
RECOURSE AGAINST OTHERS. No director, officer, employee, incorporator or stockholder of any Guaranteeing Subsidiary, or any of
their parent companies (other than the Issuer and the Guarantors) shall have any liability for any obligations of the Co-Issuers
or the Guarantors under the Notes, the Guarantees, the Indenture or this Supplemental Indenture or for any claim based on, in respect
of, or by reason of such obligations or their creation to the extent permitted by applicable law. Each Holder of the Notes by accepting
a Note waives and releases all such liability. The waiver and release are part of the consideration for issuance of the Notes.



5.          NEW
YORK LAW TO GOVERN. THIS SUPPLEMENTAL INDENTURE WILL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW
YORK.



6.          TRUST
INDENTURE ACT CONTROLS. If any provision of this Supplemental Indenture limits, qualifies or conflicts with another provision which
is required to be included in this Supplemental Indenture by the TIA, the provision required by the TIA shall control as if this
Supplemental Indenture were qualified under the TIA. If any provision of this Supplemental Indenture modifies or excludes any provision
of the TIA that may be so modified or excluded, the latter provision shall be deemed to apply to this Supplemental Indenture as
so modified or excluded, as the case may be.



7.          COUNTERPARTS.
The parties may sign any number of copies of this Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.



8.          EFFECT
OF HEADINGS. The Section headings herein are for convenience only and shall not affect the construction hereof.



9.          THE
TRUSTEE. The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this
Supplemental Indenture or for or in respect of the recitals contained herein, all of which recitals are made solely by the Guaranteeing
Subsidiaries and the Co-Issuers, and the Trustee assumes no responsibility for their correctness.



10.         SEPARABILITY
CLAUSE. In case any provision in this Supplemental Indenture shall be invalid, illegal or unenforceable, the validity, legality
and enforceability of the remaining provisions shall not in any way be affected or impaired thereby.











IN WITNESS WHEREOF, the parties hereto have
caused this Supplemental Indenture to be duly executed and attested, all as of the date first above written.



| | TELESAT LUXEMBOURG S.à r.l.
| | ---------------------------
| |                            
| | By:                        
| |                            
| |                            



[Signature Page – Supplemental
Indenture]











| | TELESAT HOLDINGS INC.    
| | -------------------------
| |                          
| | TELESAT INTERCO INC.     
| |                          
| | TELESAT CANADA           
| |                          
| | TELESAT SATELLITE GP, LLC
| | By:                      
| |                          
| | TELESAT SATELLITE LP     
| | By:                      
| | By:                      
| |                          
| | By:                      
| |                          
| |                          
| |                          



[Signature Page – Supplemental
Indenture]













| | SKYNET SATELLITE CORPORATION                
| | --------------------------------------------
| |                                             
| | TELESAT INTERNATIONAL, L.L.C.               
| | By:                                         
| |                                             
| | TELESAT BRAZIL HOLDINGS LLC                 
| | By:                                         
| |                                             
| | TELESAT NETWORK SERVICES, INC.              
| |                                             
| | TELESAT NETWORK SERVICES
INTERNATIONAL, INC.
| |                                             
| | TELESAT NETWORK SERVICES
    HOLDINGS L.L.C.
| | By:                                         
| |                                             
| | TELESAT SATELLITE HOLDINGS
CORPORATION      
| |                                             
| | INFOSAT ABLE HOLDINGS, INC.                 
| |                                             
| | INFOSAT COMMUNICATIONS GP INC.              
| |                                             
| | INFOSAT COMMUNICATIONS LP                   
| | By:                                         
| |                                             
| | By:                                         
| |                                             
| |                                             





[Signature Page – Supplemental
Indenture]















| | ABLE INFOSAT COMMUNICATIONS, INC.
| | ---------------------------------
| |                                  
| | By:                              
| |                                  
| |                                  



[Signature Page –
Supplemental Indenture]











| | TELESAT LLC
| | -----------
| |            
| | By:        
| |            
| |            



[Signature Page –
Supplemental Indenture]













| | EXECUTED and DELIVERED as a DEED
| | --------------------------------
| | for and on behalf of            
| | TELESAT (IOM) LIMITED           
| |                                 
| | By:                             
| |                                 
| |                                 
| |                                 
| | EXECUTED and DELIVERED as a DEED
| | for and on behalf of            
| | TELESAT (IOM) HOLDINGS LIMITED  
| |                                 
| | By:                             
| |                                 
| |                                 
| |                                 
| | EXECUTED and DELIVERED as a DEED
| | for and on behalf of            
| | TELESAT INTERNATIONAL LIMITED   
| |                                 
| | By:                             
| |                                 
| |                                 



[Signature Page –
Supplemental Indenture]











| | TELESAT SPACE PARTICIPAÇÕES LTDA.           
| | --------------------------------------------
| |                                             
| | TELESAT BRASIL CAPACIDADE DE
SATÉLITES LTDA.
| |                                             
| | TELESAT BRASIL LTDA.                        
| |                                             
| | TELESAT SERVIÇOS DE
TELECOMUNICAÇÃO LTDA.   
| |                                             
| | By:                                         
| |                                             
| |                                             



[Signature Page –
Supplemental Indenture]











| | THE BANK OF NEW YORK MELLON, as
| | -------------------------------
| |                                
| |                                
| | By:                            
| |                                
| |                                



[Signature Page – Supplemental
Indenture]