This OID selects the timing pattern for when the ringing signal pulses on and off when a call arrives on the two-wire source line. Network engineers configure this to match the regional phone system standard so incoming calls produce the expected ring pattern that users recognize as an incoming call. A typical North American pattern is 2 seconds of ringing followed by 4 seconds of silence, while European patterns may use different intervals like 1 second on and 4 seconds off.