A network interface device includes a first interface operable to receive at
two incoming calls over a subscriber line, and a second interface operable to facilitate
communication between the first interface and a first telephone line and between
the first interface and a second telephone line. The second interface is also operable
to generate one or more first ring voltages on the first telephone line and one
or more second ring voltages on the second telephone line. The network interface
device also includes a processor coupled to the first interface and the second
interface. The processor is operable to instruct the second interface to generate
the first and second ring voltages in response to receiving the incoming calls.
The processor is also operable to allocate the first and second ring voltages among
the first and second telephone lines to ensure that a total instantaneous load
placed on the second interface does not exceed a determined threshold level.