Investors will soon find out if Juniper's (JNPR) - Get Report four-year growth streak appears to be in grave danger.

The Sunnyvale, Calif., Internet gearmaker is due to report first-quarter earnings after the market's close Wednesday. Barring a surprise surge in sales, Juniper will deliver less revenue than it did in the fourth quarter.

Juniper had been one of the rare tech shops that consistently delivered sales growth and strong profits while rival


(CSCO) - Get Report

stagnated and peers like







Juniper's products enjoyed strong demand as telcos went shopping for big routers to help manage the traffic at network junction points. But the market has cooled, and Juniper hasn't found a new growth cycle to offset the decline.

So now, when big spenders ease off a bit, the adjustment shows starkly on the top line.

For example, in the first quarter sales to No. 2 telco


(VZ) - Get Report

slowed as the phone giant reassessed its equipment needs. The MCI acquisition gives Verizon plenty of core infrastructure, and it is expected to shift spending to edge and access areas of the network.

Also, some analysts see Japan's



as a building source of woe for gearmakers.

We "expect weakness in Japan to continue at least until the year end," said Merrill Lynch analyst Tal Liani in a research note Monday.

Juniper's stock went into a steep fall in January, dropping 19% the day after company executives

warned of a weaker financial performance in the first half of the year. The stock has recovered somewhat, largely on takeover rumors, but remains about 10% below its pre-warning level.

Analysts expect Juniper to report adjusted net income of 19 cents a share on $571 million in revenue. That compares with a 20-cent pro forma profit on sales of $575 million in the fourth quarter.

And while expectations are soft for the first half of the year, analysts expect the company to rally in the second half with more than $600 million in sales in the third and fourth quarters.

Expect a dour response from Wall Street if Juniper's outlook isn't quite that sunny.