Model names, if they follow a pattern, can tell you a lot about the product at a glance. The last two digits of BMW sedans indicate the engine displacement for example: A "323i" has a 2.3 liter engine.

The same is true with Sony Ericsson smartphones, their names reveal a lot about a model's functionality. To find out how, click read more.

From Wikipedia, here's a listing of what the first letters mean:

• F series - Mid range mobile phones. Vodafone and Vodafone partner network operator exclusive.
• J series - Low end candybar mobile phones. Do not feature cameras. ("Junior")
• K series - Low to high end candybar mobile phones. Feature cameras with dual front design. ("Kamera" Swedish)
• M series - Mid range Symbian OS smartphones. ("Messaging")
• P series - High end Symbian OS smartphones. ("PDA")
• S series - Mid to high end swivel mobile phones. ("Swivel")
• T series - Low to high end candybar type mobile phones and a carryover from the former Ericsson line of mobile phones. Later branched off into the K series and the J series.
• V series - Mid to high end mobile phones. Vodafone and Vodafone partner network operator exclusive. ("Vodafone")
• W series - Low to high end Walkman mobile phones. Feature more sophisticated media players. ("Walkman")
• Z series - Low to high end clamshell mobile phones.

If you'll allow me to add my own:

• D series - T-Mobile branded variants (The D750i is currently the only phone in this line)
• R series - Old Ericsson models still supported by Sony-Ericsson, like the R310

I also found that the suffix lowercase letter also signifies the region:

• a - North American
• c - Mainland China
• i - International

Some sample uses:

• "Ha ha! Mom got you an F500i! Check out my new P990i!"
• "Look, I took this with the K800i."
• "Ow! Don't open your S700i so close to me!"
• "Nice sounds on your W950i."