Ask yourself the question. Is your phone system one of your business mission critical applications?
Is it important that the company that services your phone system carries spare parts locally (close at hand)?
Is it important that the engineers who work on your system are accredited by the manufacturer, and that the accreditation is regularly reviewed?
And when you have an incident, is it important that your call is answered any time of day? And prompt onsite technical help availabillity?
If yes, then for Business Continuity, you should have a Service Level Agreement with GlobalTalk. Complete Support for your business