Calling card manufacturers usually change access numbers when they change carriers. The result is that they have some batch of cards with the old access number and some new batch with the new access numbers. Sometimes even up to 3 access numbers thus causing PINs to be invalid when using a different access number. Please make sure to try ALL the access numbers that were given to you before contacting us. Most of the time, using a wrong access number causes ‘Invalid PIN problem.’ However, if you tried all the access numbers and it is still not working, please do not hesitate to contact us right away.