* Estimates a 14 pct fall in full-year revenue
* Estimates fourth-quarter revenue at lower end of forecast
* Says to make acquisitions to return to growth
* Shares fall as much as 15.6 pct
(Adds analyst comments, background; updates share movement)
Jan 9 (Reuters) - British telecoms testing company Spirent Communications Plc said full-year revenue would likely fall by about 14 percent after some major equipment makers in the United States delayed awarding contracts in the fourth quarter.
The company's shares fell as much as 15.6 percent, making it the top percentage loser on the FTSE-250.
Spirent, which tests ethernet networks and 3G and 4G wireless networks and devices, said it expected revenue to fall to about $413 million in the year ended Dec. 31 from $472.4 million a year earlier.
The company also estimated fourth-quarter revenue of about $115 million, the lower end of its forecast.
Spirent's clients include Cisco Systems Inc and Nokia.
The London-listed company cut its fourth-quarter revenue forecast in October due to delays in customers taking delivery of its products.
Estimates given on Thursday underlined that 2013 was difficult and 2014 would also be tough for the company, Jefferies & Co analyst Lee Simpson said.
He lowered his rating on Spirent's stock to "hold" from "buy" and cut the price target to 103 pence from 150 pence.
The company needs to increase investment in its businesses this year and focus on a shift from a hardware-backed business to cloud-based software services, Simpson said.
Spirent said it intended to focus on developing virtual test systems. The company was also looking to expand its services in cyber security testing, a spokeswoman said.
Spirent stands to gain from Chinese clients, Simpson said. "I presume LTE (long-term evolution or 4G) will be a key area for them," he said.
In December, China awarded 4G licences to large telecom players in the country.
The roll-out of 4G in China in the first half of 2014 will help Spirent peer Laird Plc, Liberum Capital Eoin Lambe said in a note on Thursday.
Analysts believe a consolidation in the industry is likely.
Spirent said it was looking at selective acquisitions to return to growth.
Whether the company will play the role of a consolidator remains to be seen, Simpson said.
The company's shares were down about 12 percent at 87.17 pence at 1102 GMT on the London Stock Exchange.
(Editing by Supriya Kurane and Kirti Pandey)