Unless otherwise agreed (in writing) elsewhere, the service is month-to-month with 15 day notice required for cancellation or downgrades. Notice must be sent in writing via https://secure.panetma.com/submitticket.php.
For example, if your billing cycle is from the 23rd to the 22nd day of the month and you want to make a change on your account which will be effective on September 23rd, you must provide notice before September 8th. If you provide notice after September 8th, the change will be effective on October 23rd.
The same terms apply if, for business reasons, the cancellation is initiated by PaNETma.