Bill, I guess Joe and Chris have said it all.
I’d just like to amplify whatever Joe and Chris have stated. It is quite difficult to come up with peak hour traffic estimate for any particular account at hand other than the past statistics and experience;especially if you have an Offsite-Offshore BPO model.
Service levels issues are dependant upon the clients and their requirements. If they pay you per-seat-per-hour service level and incomming call load is not the core issue. However, if the client is pedantic about service level then you have to be meticulous about peek hours and all that and in addition to this you need market intelligence from your client.