In the wake of our coverage of the MPLS\/Frame Relay Alliance's approval of an implementation agreement for tunneling leased-line traffic through Multi-protocol Label Switching networks, the group approved another, related IA for voice trunking. This IA specifies a common way to transfer compressed voice, dialed digits, fax, signaling information and data directly over MPLS.The spec relies on existing ATM Adaptation Layer 2 (AAL2) technology, omitting the overhead associated with encapsulating voice in IP first.\u00a0 The IA is intended for use in designing interoperable multiservice edge routers, gateways and integrated access devices - gear you might eventually use to hand off packetized voice to a carrier service running on an MPLS backbone.Piece by piece, the telecom community is outfitting MPLS with the technology bells and whistles it needs to support the various Layer 1 and Layer 2 protocols that have come before it. This translates into collapsing networked services you have bought in the past, as well as emerging new services, onto one converged MPLS network. Behind the scenes, your carrier has a more cost-efficient way of provisioning them.So will carriers pass on the savings associated with convergence to you? That's always the question of the day.Consider SchlumbergerSema, the IT division of global oil-and-energy company Schlumberger. The company has built its own global MPLS network out of Cisco 12400 Series routers. It built its own network because it needs to reach highly remote, hard-to-reach locations. It picked MPLS for the technology's quality-of-service strengths.But Schlumberger's network is designed with segments of frame relay connecting to the MPLS backbone in the U.S. The company's networking director says this is because he has found MPLS-based VPN technology to be considerably (and inexplicably) more expensive than frame relay in this country. This runs counter to the typical sales pitch for VPN services based on MPLS technology.If you have any similar pricing-comparison experiences you can share on or off the record, please contact us and let us know how the frame-versus-VPN numbers are playing out for you.