A pulse dialing system for a VoIP modem includes a subscriber line interface circuit (SLIC) for interfacing analog telephone signals to digital signals, a relay for selectively connecting a telephone set with a public switched telephone network (PSTN) or with the SLIC, and a control means, coupled to the SLIC and to the relay, for receiving a digit of a dialed telephone number and for controlling the relay to connect the telephone set with the PSTN and with the SLIC alternatively for a number of cycle(s) equal to the digit of the dialed telephone number so as to generate pulse dialing signals to the PSTN.