I have been receiving calls from this number at all, mostly early in the morning and ending around 6am.

The phone numbers 281-295-4882 and 281-295-4886 have called my home phone 10 times in the last few days and a recorded message asks for a PIN number. If I call the number myself it is always busy.  One time I typed in some random numbers to see what would happen.  It gave me a number to call but I missed writing down the first digits.   I believe it was either 888-426-8801 or 800-426-8801.   There is no indication on the caller ID or in the message of who the call is coming from or what the PIN number is supposed to apply to.   They called at the following times that were still recorded on my caller ID:  10/7/2008 7:01 PM,  10/8  6:51 and 7:22 PM,  10/9 7:26 PM, 10/10 6:53 and 6:59 and 7:06 PM, 10/11 7:26 PM.  Reverse number lookup online tells me that the numbers belong to a land line in Sugar Land Texas.

Are you in any clinical trials?  If so, that's the ID they are asking for, and it's a reminder to enter your info.

That makes sense.  Am in a clinical trial, and today is the reporting day.

Has called several times today, does not leave a message. No caller id info available, but in looking it up it's a Sugar Land, Texas number