Calls from this number are from a bunch of scammers.
Simply googlge search for 'global tech scam' for more details.

A company called Global Tech have been calling me incessantly about a "once in a lifetime opportunity". They are very aggressive with their sales pitch. They are trying to sell software for investing in the stock market. I looked them up online and found out that it's a scam.

http://forums.whirlpool.net.au/archive/2335991

Don't get fooled. They're very convincing.