What's the impact of the SBC/AT&T merger on each carrier's vendors?

Investment firms report that the combination could be beneficial for Adtran, Ciena and Sonus, neutral for Cisco and Juniper, and negative for Avici, Lucent, Nortel and Tellabs.

First, the supposed beneficiaries: Adtran is a DSL supplier to SBC. The combination of two large carriers tends to reduce capital spending while binding up the acquirer with operational and integration challenges. SBC now has two integration challenges with AT&T and AT&T Wireless.

That could reduce spending and ambition on SBC's Project Lightspeed fiber rollout, which means more time for Adtran to establish a DSL footprint, according to a Merrill Lynch report. SBC's Lightspeed vendor Alcatel wouldn't necessarily miss out because Alcatel is also a DSL supplier to SBC - and as fiber spending is delayed, the carrier will still spend on DSL, according to Merrill.

Ciena could benefit because it does business with both SBC and AT&T, though each is "well below" 10% of Ciena's sales, reports Jefferies Research. But SBC is likely to funnel more traffic over the AT&T long-distance network, which is comprised of Ciena CoreDirector transport systems.

Sonus could become the "potential winner" in the SBC/AT&T combination, Jefferies reports. Sonus equipment forms the basis of AT&T’s CallVantage consumer VoIP service, and SBC rated CallVantage a "top notch" product that could save it lots of time, money and development costs associated with rolling out VoIP.

"It sounds like the combined SBC/AT&T organization will move forward with the CallVantage service offering and Sonus might win an opportunity to sell additional infrastructure to the combined entity," states the Jefferies Research report.

Enterprise data is not likely to see a slowdown, either. Indeed, the enterprise market is a key driver of this marriage.

So it's not likely that Cisco, a supplier to SBC, will see any slowdown. Nor will Juniper, which could ride Verizon's expected enterprise expansion in response to the SBC/AT&T marriage.

However, some "weaker players" such as Avici, which is AT&T's core IP router supplier, may be "shut out," according to Merrill.

Not so fast, says Avici CEO Bill Leighton.

"SBC acquired AT&T for three things: its brand, enterprise customers and its global network. We power their global network," Leighton points out. "We actually view it as encouraging. If they bought AT&T for its network it's going to go over our routers."