For the previous question – What value you must use?
In the ITU-T recommenadations E.xxx is said that you must take into account at least 30 records for the BH (these records must be only in one category – working days, weekends, yearly esceptional days /Christmas, Easter and so on./) The second highest value is the high load traffic, the fourth is the normal load traffic. The network must be estimated for the normal load, but must fullfil other requirements. For PSTN networks these GoS values are – 1% and 7%. Usually the second demand is harder for carrying out.