Essentially for your centre GOS is the % of calls answered within 30 seconds / total number of calls received. Where you start counting calls received is always a debating point but we would always advise you do the calculation from the point where an agent may receive the call. That means, expanding on Jonty's post above, you measure service level after the customer has been through the IVR choice and put into the agent queues.

At this stage I wouldnt exclude any calls, although it is pratice with some businesses as Jonty says to exclude short length abandons - I would rather suggest you monitor these figures as they identify customer behaviours, e.g. impatience which could be managed by changing messages giving them an expected wait length.

It would be useful to see the equation your IT dept uses as I could assist with some arguments for or against in terms of industry practice. I did have a look at Trixbox website but struggled to add any light on the question.

My understanding is that the main formula for Service Level is

SL = number of calls answered within threshold/ number of calls offered.

However some systems will exclude all calls shorter than 4 seconds as it may be the case that some people may have dialled the wrong number.

It gets a bit more complicated if you have an IVR. Some people only start the count once the call has exited the IVR. Since IVR abandons average 13%, this could produce quite a skew in the stats.

I use a Trixbox phone system in my call center we are way below the required GOS of 85% of calls answered in 30 seconds our it department has some formula that it uses to calculate our grade of service that both I and the retention Manager disagree with can anyone assist