A service package on a number can include bundled minutes, call features and a monthly fee. Not every package type is defined with all three, but it is very unlikely for a package to include bundled minutes and NOT have a monthly fee.
Some packages may also provide preferential call rates.
You can think of a service package as a mini-tariff.
See telecoms.num.svcopt.list to see which service packages are
available on a given phone number.