An apparatus and methods for Real Time Protocol (RTP) based bridging to create calls to and From any communication devices connected to the Public Switched Telephone Network (PSTN) or any public or private Internet Protocol network. The methods are represented in controls residing either in an RTP Bridge apparatus or as middleware on a service creation platform, softswitch, or SIP proxy services incorporating SIP bridging and SIP call relay technologies, with an interface to a TDM (Time Division Multiplexing) switch operated by a Local Exchange Carrier (LEC) or Competitive LEC (CLEC), or hosted by an Internet Telephony Service Provider (ITSP) with connectivity to the PSTN through media gateways. The method permits a party to request an on demand conference call by either dialing into the apparatus from the PSTN or from any type of RTP communication device such as an IP phone; or using a form of signaling from RTP translation device. The moderator initiates the request, enters the participant(s) to be included in the call, and the launch sequence is initiated and the apparatus makes contact with the phone / end point and uses RTP bridging to interlace the packet streams and deliver one stream back to all the devices. The advantage is an on demand conference call to one or many participants, on similar or different communications platforms.