GSM Modem Help Please!

This is the product (GSM modem) that I'm planning to buy. LINK- OR

Which of these is better and what's the difference b/w them? Though it says a RS232 connector, it has got 5v, gnd, Rx,Tx(TTL) connectors on the pcb.So can I use it with the arduino using those TTL connectors or would I need a RS 232 ro TTL convertor Like this -

PLS Also state regarding how to use it in brief if POSSIBLE.

Here's another one which seems to be a better GSM modem because it says they have got datasheets and other imp infos unlike the ones that I put in link earlier.Please also review this one!