Did not recognize area code , so let it ring til it quit

Card member services wanting to lower my interest rate on my credit cards. Phone number is Colorado but rep said they are located in Miami FL. Everyone who is registered on the Do Not Call list needs to file a complaint.

I live in Alabama.  Just got a call from this number today, May 31st, 2016.  Did not answer as I was asleep, but they left no message, which is usually an indication of robocalling, telemarketing, or unethical shenanigans of some kind!  My first time getting call from this particular number, but personally I have recently (last 2 months maybe?) seen a HUGE rise in the number of "spam" calls I've been receiving.  I hate to change my phone number as I've had it for 13 years, and boy what a hassle that is.

I've been registered (and have confirmed multiple times that I still am) for many years with donotcall.gov -- but that only helps with organizations that are legitimate and thus cooperate with the applicable regulations set up when the site was established.  I don't know that registration there has any impact at all on all these calls most of us are getting -- usually faked numbers.  Does anyone know anything I can do (besides continuing to add numbers to my block list, which now probably has 30 numbers!) to help reduce the number of these spam calls?  I've received four today!  Thanks so much.

Called today. Caller ID stated Bank Card Asst.  Yep, they want to assist you out of you personal information and money.  Of course, didn't answer.

Call to lover interest rates.