The mergers, which will radically change the US telecommunications market by merging the two biggest local phone companies with the two biggest long-distance carriers, are expected to close later this year or early next year.

The FCC vote to approve the deals with conditions was unanimous, but appeared to represent a compromise. Commission Democrats wanted to push for more conditions, the Republicans fewer. The merging companies all agreed to the conditions.

I do not believe that all of the conditions imposed today are necessary, Republican commission chairman Kevin Martin said. I believe that the affected markets would remain vibrantly competitive absent these conditions.

Commissioners on the other side of the aisle were not as confident. Based on my weighing of these potential benefits and harms, I could not support these mergers in the absence of reasonable conditions, Democrat commissioner Jonathan Adelstein said.

Without conditions, there is a real possibility that these combinations would increase rates for both residential and business consumers and put at risk the continued existence of the open and robust internet, he said in a statement.

Among the conditions, which will be monitored and enforced by the FCC, are price freezes on unbundled network element services – UNEs, where carriers rent equipment and lines to competitors – for two years.

Also, for 30 months the companies have agreed not to increase rates paid by existing customers of AT&T in SBC’s regional franchise or of MCI in Verizon’s region for wholesale DS1 and DS3 private connections.

In terms of the internet’s backbone, where AT&T, MCI and SBC are considered Tier-1 carriers, the two newly merged companies have to agree to maintain the zero-settlement free peering arrangements they have now for at least three years.

The approval of the deals came after weeks of negotiation and at least nine months of study. The final conditional approval was delayed several times as last-minute details were ironed out.

In many respects, the approval of the deals – subject to additional conditions not listed here that can be found on www.fcc.gov – went to the heart of a long-running ideological debate over the direction of US telecoms policy.

The big carriers had argued that the mergers were required so they could remain competitive in the face of alternative communications services. This is inter-modal competition, between cable and copper and emerging mediums like WiFi.

But some commissioners, and consumer watchdogs, have argued that intra-modal competition, competition within the same technology group, has been sacrificed at this inter-modal altar.

The FCC put intra-modal competition for the residential market pretty much beyond reach for new entrant carriers, commissioner Michael Copps said. And all the while we kept singing confidently ‘Don’t Worry, Be Happy’ – inter-modal competition is going to save us.

Maybe, but then again maybe not – we’re still waiting, he wrote. I think we ought to be concerned.

On the flip-side, proponents of lighter regulations, such as commissioner Kathleen Abernathy, said that the fast-moving communications industry and pace of innovation warrants giving carriers more flexibility.

Technological advances that spurred competition now allow us to consider mergers that might have been unthinkable in the ‘natural monopoly’ pre-convergence era, she wrote. Dramatic changes in the technology, the economics, and the structure of the market have mooted prior concerns.

The US Department of Justice has approved the mergers, with the proviso that the companies sell off dark fibre links into buildings where they would have a post-merger monopoly. A handful of state regulators have still to rule.