I would suggest first of all that you investigate the availability of MA TESOL courses, and then, above all, the cost. Bear in mind too, that even a distance course will require some on-campus presence. If the distance course is delivered by an internationally recognised university, it will of course be accepted everywhere without the slightest problem. Be aware however, of diploma mills, 'experience' degrees, and degrees offered by 'universities' with addresses in tax havens such as the Cayman Islands, and certain universities in Africa and the Middle East. For the kind of work you will be seeking, the deans and personnel departments carry out serious checks.