This attribute specifies the allowed customer defined parameter of
the trunks on the route. The value of requiredCustomerParm ranges
from 0 to 7. The meaning of each value is specific to a particular
network, thus allowing them to customize the use of their trunks. A
complementary trunk attribute, customerParameter, also has a value
from zero to seven. The route selection process does not consider
trunks whose customerParameter is greater than the
requiredCustomerParameter of the path.