Got a random text message from them asking me to call them.  They refuse to tell me who they are.

Do not respond to unwanted texts or emails from questionable sources. Several mobile service providers will allow you to report unwanted spam texts by simply texting/forwarding it to 7726 (or “spam”) to enable the providers to prevent future unwanted texts from the specific sender.

(If your provider is ATT, try the code "block")

Source:
http://www.fcc.gov/guides/spam-unwanted-text-messages-and-email

More info:
http://en.wikipedia.org/wiki/Mobile_phone_spam
http://blog.usa.gov/post/89152807112/protect-yourself-from-text-message-spam

However, in many cases, the text origin, as seen on your phone, is faked.  The internet domain does not exist, or the phone number may have been spoofed.

Received the same text "please call me" not going to call. Seems to be a scam.

Just got a text from this number asking me to "please call me".  Yeah like that's going to happen.  I don't answer texts or phone calls from numbers I don't know.

Same as others. Text asking me to call. Not going to happen.