Research In Motion's shares slid in late trading yesterday after projecting lower-than-expected subscriber adds for the current quarter. RIM projected 675,000 subscribers for the first fiscal quarter, but investors expected between 700,000 and 750,000. Remember that RIM lowered guidance on fourth-quarter subscribers twice. The main explanation was that uncertainty around the NTP patent was delaying purchases. So what's the reason for lowered guidance in this quarter? Are BlackBerry alternatives making an impact? UBS seems to believe the company is being conservative since RIM said it is hearing positive indications from customers and channel partners that they have strong BlackBerry roll out plans going forward. Meanwhile, RIM said it was operationally ready to move forward with BlackBerry service in China and expects the initial service launch to be nationwide across all 30 provincial operators that comprise the China Mobile network.