BHT in average = 60 secs in short
BHT in average = 180 secs in long
Although is 100% available but normally the traffic is very low which compared with local telephone lines.
Therefore we need to dimension in different type of trunks:
1. DID line for hotel,
2. DOD line for extn., direct line.
Different GOS will be used to dimension these two trunk type.
1. for DID – 0.5% GOS
2. for DOD – can be divided into seperate trunk group with overflow facility to ensure no blocking. For initial trunk group – 30% overflow and 0.5% GOS for final route.
Nevertheless, it will depend on the equipment investment from the company.