That phone is the L5 of the LG L series. Its underclocked from a 1ghz down to 800mhz.
I have that phone. I use the BYOD SIM and i put it in that phone and works with no problems. The tmobile SIM will not work in it. Its locked to att. The battery life is very good. The reception is awesome. I would recommend it. THe screen IMHO looks bigger than a 4inch one. Sound quality is good. I like it. I do wish it was a little cheaper.