You can buy a Goodybag once and it will last for a month or you can set it recur monthly.
Goodybags include "UK minutes" for the following:
* calls to 01 and 02 numbers (not including Jersey, Guernsey or Isle of Man)
* calls to 03 numbers
* calls to standard mobile numbers beginning 071-075 and 077-079 (not including Jersey, Guernsey or Isle of Man)
* calls to voicemail on 443 (each call takes one minute from the allowance)
All other calls, such as 084, 087, 09 premium rate, etc are charged as listed here and need separate call credit.
Calls from the UK to international destinations are listed here and need separate call credit.
Once the allowance is used up, calls to the numbers listed above revert to the pay as you go rates for the remainder of the month. You need separate call credit for these calls.
Goodybags also include an allowance of texts and internet usage.
Once that has been used up, the pay as you go rates also apply and need separate call credit.
If you do not have any separate call credit or "Airtime" loaded, then you cannot make any calls other than what comes in the Goodybag allowance.
You have to top up with £10.00 the first time, so you will have £2.50 left over for this use.