Does your company have an internal Help Desk? How many calls do they handle? How long do they spend on average on the phone? Is there one member of staff not pulling their weight? Is there one member of staff that is working harder than everybody else? Are they taking their breaks at the best time, or is cover required during the lunch breaks?
Telephone Call Logging should produce reports allowing you to see the busy hour on a group of extensions and trunks if your helpdesk receives calls from outside your building. You can run performance reports to identify (broken down in a time slot period) how many calls are being dealt with each hour, how quickly those calls are dealt with and how long callers were kept ringing. Do you need more bums on seats to deal with these calls?