Where can additional call credit be topped up?

The call credit can be charged by credit card in the dashboard under Administration. If you do not have a credit card available, you can top up your call credit by going to the support form at https://www.tracker.com/en/supportform. Write in the field 'Problem description' the conscientious "top up call credit CHF ... .." and we will send you an invoice by email. The call credit will be available after payment.