It sounds like a programming issue. Hopefully, some of these resources will help:https://www.nconn.com/pdf/Toshiba%20%20Strata%20DK%20Programming%20Manual.pdf https://www.mainresource.com/PDFs/ToshibaStrataAdmin.pdfhttps://www.ask-tsc.com/pdf/Strata_DK_Digital_Telephone_Users_Guide.pdf