It is Sprint calling.  You can block the number this way and never worry about it again:

Log into your Sprint account.
Click on My Preferences tab.
Scroll down to Limits and Permissions and click on Block Voice.
A new menu opens, now click on the device to have the number blocked on.
Click the button next to "Block only the following phone numbers for inbound and outbound calls"
Type in the phone number in the box.
Click "ADD" button.
Click "Save" button.
This works for any annoying calls you get on a Sprint phone.  (I believe it allows up to 50 blocked numbers.)

I have Sprint and was told I would receive a survey soon - didn't realize it was Sprint until I looked here but will try to answer next time as they were most helpful.

This is a call from Sprint, wanting you to take a customer service survey>

HAHA its an automated survey from a company called Advantis that does customer service surveys for companies.  I'm sure all of Sprint's competitors do the same thing.  

If you are concerned about using a couple cell minutes to check a voicemail in 2012, i feel bad for you.  That is just sad.

it is illegal for them to do this. its called harrasment ...also what i do is when they call i answer and hang up right away the first time this happen they called me three times in a row at first i thought it was someone trying to crack into my phone the i read the forums and seen im not the only one there calling from the same numeber and if someone calls me from india i wont talk to them anyway ill ask them to tranfer me to america and when they dont .....CLICK....goodbye...anyway just wanted to share with you all...thanks

twice now this number has left me a v.m., which costs me minutes on my cell phone to listen to.  I would like to know who this is.

go f*** yourself

Missed call from 866-888-5233 - with no caller ID.   I will never return a call if I don't know who I am calling.   I am on my son's account and they continue to harass me with text messages and now this unidentified caller which I have learned is  Spring.  Hope the FCC can stop this.

This was a Sprint Survey call.  I was able to call the number back and complete the survey.  The staff at the store let me know ahead of time that I would be getting a call.

It is a satisfaction survey from Sprint. Be happy that they care enough to get customers input on their visits

866-888-5233 is for Sprint Survey. I recently visited an independent Sprint Store in a small city and this call was for feedback as to my experience at that location. The call to this number is not deducted from your minutes; it is absolutely free and I recommend completing their surveys in order to improve their service.

This call came in from NEXTEL, its a short survey.  I wallked in SPRINT on Saturday to activate my new phone and they wanted to know how the services was. Its an automatecd call.

I recently setup a new sprint account and the next day I received a call from 866-888-5233 I let it go to voice mail but no message. I called it back just a few minutes ago after reading these postings. It's a sprint automated survey system asking how your most recent visit to the sprintpcs store was with only a few questions. No big deal people

It is sprint but they appreciate the feedback about your experience whether good or bad. %f there is something you want to change you have to make a difference and take the survey! They even have them for calls when you spek to a rep on the phone and they as you if you were surveyed would you say they resolved your issues..

got a voicemail from this #...guy said my name several times and then said "I am a big fan of yours"...call me.  I checked it out on internet and called the # from my work #, it is Sprint. what a stupid comment to make on a message.  we did have our phones updated in the store recently.  they need to talk to their employees about leaving messages with heavy breathing...glad i didn't answer.

This is Sprint. After getting assistance from customer service or visiting a store they send you a survey to rate your experience.

i BEEN RECIEVING CALLS FROM THIS NUMBER, NOBODY TALKS, NEITHER WHEN YOU CALL BACK IT IS RESTRICTED,....THIS IS A SHAME AND I THINK ITS ILLEGALE....DONT WANY TO RECIEVE THESE NUMEROUS CALLS AGAIN....

I received a call from 866-888-5233 today. It's the 2nd time this number has called my cell phone.

I keep recieving unknown calls no matter the time...I don"t like to keep recieving those calls.

i am recieving calls on multiple times, without nobody letting messages, please sombody stop these unknown calls......

Sprint customer satisfaction survey.  I answered their survey questions and then the call ended.

I tri to make calls from this number to get cust feadback for my suprvisor, and Im gettinga kick outa these replies.

Its Sprint/Nextel.

According to a similiar website, this is a survey call from Sprint.  I let it go to voicemail.  No message left.

Got a call and didnt leave a voicemail.

Sprint/Nextel -left no message - I just updated my phone

Sprint/Nextel - no message

This is annoying.  No message also, and they called my cell twice.
I already switched and upgraded my phone and asked for no text messages from Sprint, etc.  I intend to tell them this again on the next bill.

I've received these calls on several separate incidences.  It's always a couple of days after I make a change to my SPRINT account.  I never answer strange calls like this, and they never leave a message, but from reading a few different forums, I'm sure it's SPRINT EMPLOYEE(s) making these calls.  I think SPRINT'S main customer service is located in INDIA and that's where the calls originate from.  I don't know if SPRINT/NEXTEL'S corporate office is aware of this activity, or if it's just a handful of their employees who are doing it.  They have access to your cellular number, and I wonder if they have access to all of your account info, (credit card #, address, etc..)?  ILLEGAL???  I'm going to forward this info to the FCC, maybe they will look into it.

I JUST e-mailed THIS TO THE FCC @ 'fccinfo@fcc.gov':


SOMEONE CALLING CELLULAR PHONES FROM (866) 888-5233

JUST TYPE THIS NUMBER INTO GOOGLE, AND LOOK AT SOME OF THE FORUMS.

I've received these calls on several separate incidences.  It's always a couple of days after I make a change to my SPRINT account.  I never (CONTINUED SAME AS ABOVE).