VIEWSONIC PS500B - Manual (Page 15)

PS500B/PS800B 7
2.8 Data-Line Surge Suppression
The data-line surge suppression on the rear panel provides an easy way to
protect a network (RJ45) or modem (RJ11) connection from hazardous spikes.
Connect a 10/Base-T network cable or a single line telephone into the “Line”
socket. To complete the connection, connect another network cable or
telephone line into the “System” socket. The network cable and telephone line
are optional accessories, which may be purchased from your local dealer.