According to a research note issued today by UBS Investment Research, the number of equipment vendors still competing to supply Gigabit passive optical networking (GPON) gear to Verizon Communications has been narrowed to four.

The so-called “short list” of vendors whose equipment will be further tested in Verizon’s labs is Alcatel, Hitachi Telecom USA, Motorola and Tellabs, according to UBS, which also predicts Verizon to select two or three suppliers from that list in the next few months. The vendors most likely to be selected to supply Verizon’s GPON deployments in 2007 are its current incumbent PON suppliers, Tellabs and Motorola, UBS said.

Verizon does not comment on ongoing vendor selections and cannot confirm or deny UBS’s report. The carrier also requires equipment vendors submitting proposals to sign nondisclosure agreements that prohibit them from talking about the process.

Though Tellabs has vowed to add a GPON blade to its 8800 edge router, the company has not formally unveiled GPON products. Marketing materials distributed by the company last December included a picture of the 1600-712 single-family GPON optical network terminal (a customer premises device) and described the 8865 optical line terminal (presumably the GPON-enabled version of the 8800). But later that month, a company spokesman called those “planned future products.” As of today, neither product appears in the comprehensive list of products on Tellabs’ Web site.

Alcatel and Hitachi Telecom USA both announced GPON products last year.

Verizon issued a request for proposals (RFP) for GPON gear together with AT&T and BellSouth last November. One analyst recently estimated as many as 18 vendors may have responded to that RFP, but others have said that, without counting partners as two separate entities, the number of bidders may be closer to eight or ten.

In today’s research note, UBS also said it was unclear which vendors AT&T would select for its GPON deployments, which UBS predicts will amount to about 4 million lines starting next year.