[header] How to control a tv with alexa [title] Check with your provider to make sure your equipment is compatible. [step] You may be able to check on their website for more information or call their support number to ask a representative. [substeps] Necessary equipment will vary between providers. 
If possible, you may also want to check that your cable box or other hardware is updated with the latest software. If you are having difficulty determining if your equipment is compatible, you can try the enabling the alexa skill anyway, the worst case is that the skill will simply not work.