As Qualcomm ( QCOM) vows to repel the hordes encroaching on its wireless turf, investors have started noticing some weak spots on the battlements.Led by Nokia ( NOK), rivals are preparing to storm the ramparts of Qualcomm's fast-growing code division multiple access, or CDMA, wireless standard. Qualcomm insists it will fight for every inch of its lucrative near-monopoly territory, but observers agree that the company can't expect to maintain its stranglehold -- Qualcomm sells close to 90% of all the world's CDMA chips -- forever. The worries have been brewing for some time, but they came to a head at a recent analyst day. Normally these sessions are placid affairs, with issues raised in earnest and put to rest with ease. But that wasn't the case last Thursday, when Wall Street's tech crowd outlined a growing list of concerns topped by pricing trends on Qualcomm's CDMA chips and phones. Focusing the spotlight on a sweating Qualcomm is a pending agreement that would allow Nokia, the world's No. 1 handset maker, to supply phones to Verizon Wireless, the nation's No. 1 CDMA telco. Qualcomm's CFO, Bill Keitel, says the alignment of those two powers is supremely good news for the CDMA industry. He points out that Qualcomm gets a royalty for every CDMA phone sold, and adds that an expanding sales base will boost Qualcomm's already strong numbers. But industry watchers warn that the competitive onslaught could slash Qualcomm's robust profit margins even if sales do rise, putting pressure on a stock that has mostly been running in place for the past year. On Friday, Qualcomm fell 45 cents to $30.90.