Yes. If the phone is assigned to a User Account, then that user can configure this by logging in at https://dialpad.com, clicking on Call Handling & Voicemail and then Advanced Options and then moving the slider under Ring Duration.
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If this is a Room Phone, it can only be changed by an Office Admin. Login at https://dialpad.com, click on Admin Settings, then select Desk Phones, and then click Room Phones, click Options next to the phone and choose Edit.