In telephony, a stimulus protocol is a type of protocol that is used to carry event notifications between end points. Such a protocol is used to control the operation of devices at each end of the link. However a stimulus protocol is not sensitive to the system state. In a typical application such a protocol will carry keystroke information from a telephone set to a central call control. It may also carry control information for simple types of text displays. MiNET from Mitel is a typical protocol of this sort.

This should be contrasted with a functional protocol such as Session Initiation Protocol (SIP).