Text them back spam and everyone hit them hard. Number comes back as AT&T Cell Number. Use http://www.onlinetextmessage.com/ and spam these turds back.
Recieved same text....an offer to modify mortgage. Please report their number to the National Do Not Call Registry. If they continue, they will be fined heavily. Get 'em where it really hurts....in the pocketbook! here's the Government Registry link: https://www.donotcall.gov/register/reg.aspx