Can I use these cheap GSM module with arduino? I found two cheap GSM module on ebay but didn't know that I can use them with Arduino or not.
Will you help me please?

Here are the link-

http://www.ebay.co.uk/itm/Smallest-SIM800L-GSM-Module-Micro-SIM-Board-Quad-band-Port-Onboard-Antenna-/111789339320?hash=item1a0729f2b8

http://www.ebay.co.uk/itm/SIM900A-Development-Board-Extension-Module-GSM-GPRS-Antenna-TTL-e/281517486292?_trksid=p2045573.c100033.m2042&amp;_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3D70128bc79b60410d862b64d36cc479b3%26pid%3D100033%26rk%3D1%26rkt%3D4%26sd%3D281517486292
The SIM900A won't work in the UK, it's dual band.
The SIM800L is cheap as there is no power regulation on board. IIRC it requires 3.4V - 4.5V, min 2 amp supply. Check the data sheet to be sure.