However, some problems cannot be fixed remotely, and support staff will be required to provide on-site assistance. Where support staff are co-located with users, this may involve no more than a short stroll down a corridor. In this case, maximising the ability to handle problems remotely can help solve problems faster and more cheaply. Depending on the level of internal user support available, for more complex problems, external user support may be required. External support is typically required when proprietary hardware or software needs to be serviced or repaired, or where problems are beyond the ability of internal support staff.
External support tends to be more expensive per hour than internal support.
The time taken to respond to requests for external support can also be an issue. External support providers may not be available to fix problems when the EMB would like them fixed, as they have their own priorities. If external support is provided at urgent notice, this usually incurs additional cost. Under an SLA, a service provider agrees to provide a guaranteed level of service for an agreed price. For example, different hourly rates can be agreed for responses to problems dependant on the level of urgency involved.