A:Answer Hello! We recommend you to verify the model of the quick connect cord that you have at school. Each cable is different depending on the phone that you have and they all look quite similar. The cable that your Avaya phone requires is an HIS cable, part number: 72442-41. If the cable you have at school is not that model, then that is probably the reason why the other end is not able to hear you. If you require further assistance, please don't hesitate to contact our Customer Care Team at: https://www.plantronics.com/us/en/support/contact