This object describes the external device type that is
connected to the serial-line type (eg, HSS, HDWAN) path. It is
applicable only for a dialup path.
Use bri(1) setting if the path is connected to a digital modem or
terminal adapter for ISDN connectivity.
Use modem(2) setting if the path is connected to an analog modem.
Use sw56(3) setting if the path is connected to a SWITCH56 CSU/DSU.
In order for any modifications to take effect, the path must be
enabled(re-enabled if it is already enable).