In most cases, either the caller ID is disabled on your mobile phone or you are calling from a phone number that is not associated with your account. Parkmobile's automated parking service relies on receiving the caller identification to immediately associate the call with a specific account. To add another phone number to your account, you'll need to login to your Personal Pages and click 'Users' on the left-hand navigation area. Then click 'Add new phone number/account' to add another user or phone number to your account.
If you need to change the phone number on your account, click 'Users' on the left-hand navigation area. Then click the link under 'Last Name' to access the already active phone number/user. There you can change the mobile number associated with that user.