Things are sure dicey at Sprint Nextel Corp. (NYSE: S) these days. The wireless carrier fired its CEO just recently, customer numbers are dropping every quarter and the company seemingly bailed out of its ambitious WiMAX network plans for fear of taking focus away from its core wireless network.

Well, one of those 'core' networks has a problem. When Nextel merged with Sprint a few years back, the Nextel network was supposed to operate alongside the Sprint network (the two networks are technically incompatible). Nobody knew how these two networks would co-exist, although Sprint says they will for quite some time. The problem is that the Nextel 'iDEN' network is causing some serious problems insofar as interfering with police and fire radio systems nationwide due to the radio frequency it operates on.

So, Sprint has something else to face now. If the company cannot repair its iDEN network -- still used by millions of Sprint Nextel customers -- by next June, it will be shut down to ensure police and fire radio bands operate without interference. This is a problem for Sprint, and it gives the wireless carrier little breathing room in terms of trying to make major modifications to an operating national wireless network in just over half a year's time. If Sprint can't pull this off, then it will have even more problems from existing Nextel customers and could lose even more of its customer base next year. Not good.

Sprint Nextel Corporation (NYSE:S) is known for being an innovative wireless company that has had many firsts and close-firsts in the mobile phone carrier game. Mobile TV, 3G data networks, wireless online music stores and other features have -- in the past -- set Sprint Nextel apart from competitors like Verizon Wireless and Alltel -- both of which use the same wireless network standard as Sprint Nextel known as CDMA.

But, as Verizon Wireless and larger competitor Cingular Wireless are adding over a million new subscribers per quarter, Sprint Nextel actually lost over 300,000 subscribers in its latest quarter. How could this be?

The carrier blamed the loss on its older iDEN network that still contains customers from the older Nextel network. Sprint and Nextel merged in mid-2005 in response to mergers from Verizon Wireless and Cingular Wireless. Nextel's radio spectrum holdings were very valuable as well, and were a key factor in the merger.

With former (and current) Nextel subscribers being some of the most loyal in the wireless industry -- from my experience -- I am perplexed over why so many Nextel subscribers have left the carrier in its latest quarter. Has Sprint given up on the Nextel network and has service gone to hell or something? Sprint's Gary Forsee will most likely be shown the door this year unless Sprint finds a way to stem customer defections and actually gain customers.