An important principle of ITIL is that all requests should go through a single point of contact (abbreviated to SPOC). What this means, is that a single channel should be defined for the reception, classification, and distribution of a request or incident. Crucially, it does not mean that all contact with the customer should be done by tier one.
Many people who work in operations and development (as opposed to support) have completely misunderstood this. They treat ticketing systems as a nuisance, and direct customer contact as something to be handled by someone else, sending tickets back to support for customer contact. This introduces a number of problems.
First and foremost, it increases the time from receipt to resolution of a ticket. Second, it means that questions will be asked to the customer by people who may or may not know the greater implications, and who may or may not be able to ask follow-up questions. Third, it means that the case will be bounced back and forth, the responsibility of everyone – and hence noone.
Happily, we can resolve these problems with relative ease; mandate that everyone use the ticket management system, and that a ticket is the responsibility of the assigned group and/or technician. If the technician wants information from the customer, it is their responsibility to contact the customer to get that information.
This is not to say that a ticket should be sent up the line without previous tiers doing their part of the job; far from it. Tickets that have not been properly described and documented should be returned to the previous tier for further work. Tickets that have been sent to the wrong duty section, however, should not be returned, but rather sent to the correct duty section.
The end goal is to resolve tickets as quickly as possible, with the highest appropriate quality possible, and at the lowest tier possible.