AT&T Mobility (NYSE:T) said it will launch its largest smartphone marketing effort ever when it debuts the flagship Nokia (NYSE:NOK) Lumia 900 April 8 for $ 99.99 with a two-year contract. The marketing push is AT&T’s biggest ever, even bigger than the carrier’s efforts to launch Apple’s (NASDAQ:AAPL) iPhone. Nokia and Microsoft (NASDAQ:MSFT) clearly have a lot riding on the LTE-enabled smartphone, which could help spark consumer interest in Windows Phone if it is a hit. FierceWireless surveyed industry analysts for their opinions on the device and whether AT&T’s marketing efforts will pay off. Here is a selection of their thoughts in this “Sound Off” feature.