I received call this morning and I have Tele-Zapper on my line which sent a signal to the caller.  I did not hear anything for 30 seconds and they hung up. I called back the number and got an intercept message: "The subscriber you dialed is not in service. If you feel you received this message in error please try again later. Message TX 06 56."
Whitepages lookup (469) 544-0742
Type: Cell PhoneProvider: T-Mobile USALocation: Grand Prairie, TX

Due to number portability, some numbers have been transferred to a new service provider.
Beware of scam.

I just received this call, talked with person, told them to remove me, and that I knew it was a scam.  I was told "it wasn't a scam", and then they hung up on me.  I tried calling this number back, and was told that the subscriber is not in service.

I called this number back;
469-544-0742,
and I was told this number was no longer in servoce, but on my machine it's telling me I can save thousands in interested charges with their credit card,and credit reporting services.
Just another scam from Africa Im sure.

(Don't actually have phone number, but found this page by Googling "Card Services". I can't guarantee this is the correct number.)

I'm also receiving "6.9%" robo calls from something calling itself "Card Services", 3 times in the last 2 weeks.
Possibly related, a May 29 2007 press release from the North Carolina Attorney General describes a company which this exact MO (behavior), called Possibilities Unlimited. They've been given a court order to stop the calls to NC customers. Not sure how to get this stopped elsewhere, since I have neither a number or proof of company identity.
Release PDF: http://tinyurl.com/2dt2nl

repeated calls from this #... recorded message about saving money with lower interest rates.. pressed the required # to speak to someone.. they answered with "card services"...requested my name to be taken off .. that person hung up on me.