To support a changing volume of a voice-grade traffic in an access network having a local exchange with a limited capacity, provide two or more access networks each having subscribers and associated local exchange with a limited capacity; each capable of dividing traffic, outgoing from its subscribers, into the voice-grade traffic portion and data traffic portion, and capable of directing the data traffic portion to a packet network while directing the voice-grade traffic portion to a PSTN network via associated local exchange. Second, detecting the overload condition on one local exchange (LE1). Third, find a remaining one (LE2) of the local exchanges in normal load condition. Fourth, partially diverting the voice-grade traffic intended for the local exchange LE1 and passing the diverted voice-grade traffic to its destination via the packet network and the local exchange LE2.