Javier…I see that happen all the time and really if you are going to use some sort of calculation you just need more information. You can _assume_ hold times of 3,5 mins, but then again that would be business level traffic. Take the calls in the interval and change that interval to 1hr. Multiply that by 210 seconds. Divide by 3600 and you will have # of erlangs. Its in accurate but it gets a number.
Alexandra…you have to do the same thing but you will have to ask them the average hold time….you need to different call centers have different hold times….operator services have an avg hold time of 9seconds and avg speed to answer of 2 seconds…something like that. While a call center taking travel trips may have an average hold time of 35 minutes with an avg speed to answer of 2,5 minutes. You need their metrics, or you will get the calculation wrong. BTW…dont forget to get the number of agents.