Shares in Waterloo, Ont.-based Research In Motion fell Thursday after it announced it was planning job cuts as it reported first-quarter revenue and earnings that didn't meet analysts' expectations.

The company posted quarterly revenue of $4.9 billion U.S. and earnings per share of $1.33. Analysts had expected revenue of about $5.15 billion and earnings per share of $1.32. RIM reports in U.S. dollars.

In after hours trading in New York, its stock was trading down $5.57, or 15 per cent, to $30.01 US.

The company was not specific about how many positions would be cut in what it called a "headcount reduction."

"This realignment will be focused on taking out redundancies and a reallocation of resources to allow us to focus on the areas that offer the highest growth opportunities and align with RIM strategic objectives, such as accelerating new product introductions," the company said in a release.

"We expect to implement this program beginning in the second quarter with the benefits impacting results primarily in Q3 and beyond."

Revenue was down 12 per cent from $5.6 billion in the previous quarter and up 16 per cent from $4.2 billion in the same quarter of last year.

The earnings of $695 million compared with $934 million, or $1.78 share, in the prior quarter and $769 million, or $1.38 a share, in the same quarter last year.

RIM lowers earnings estimates 

The company said it shipped approximately 13.2 million BlackBerrys and approximately 500,000 BlackBerry Playbook tablets during the quarter.

The company also estimated second-quarter earnings per share in a range of 75 cents to $1.05, as opposed to earlier guidance of $1.40.

It reduced its previous guidance of earnings of $7.50 a share for the full year to between $5.25 and$6.00.

"Fiscal 2012 has gotten off to a challenging start," co-CEO Jim Balsillie said in a statement.

"The slowdown we saw in the first quarter is continuing into Q2, and delays in new product introductions into the very late part of August are leading to a lower than expected outlook in the second quarter."

The firm's BlackBerry smartphone lineup has faced fierce competition, especially in the U.S., from Apple's iPhone and devices using Google's Android software.

In April, investors hammered the company's shares after it warned that first-quarter earnings and sales would not be as strong as it had earlier estimated.

Investors have called for a change to RIM's management structure, saying there should be only one chief executive and an independent chairman of the board. Balsillie and co-chief executive Mike Lazaridis also serve as co-chairmen of the company.

However Balsillie said Thursday the company's management structure is working. 

"Neither of us could have taken the company this far alone," he said.

With files from The Canadian Press