What industry standards exist for time (minutes or days) to contact a client after they have identified a problem and initiated an electronic communication with a service provider. I understand that in many cases these times are defined by SLA or are addressed in an OLA. SLAs often include criteria based on priority/urgency assigned by customer, I would expect also to be addressed in industry standards.
In the absence (or conflict) of an SLA(s) are there standard response times that are recognized as best practice?
In particular I am looking for IT industry standards, but any standards would be helpful.
Google searches for 'first contact' even after I removed 'star' did not get me what I was looking for.