I believe they are trying to collect a debt on behalf of Optimum Online. They are both tricky (call from 3-4 different phone numbers/area codes) and persistent (call sometimes up to 3-4 times per day) for what is a fairly small amount of money, $120.

Yeah, I've gotten two call the last two days. One from this number and one from out of Chattanooga, TN.
If it is a collections agency, I don't know why they are calling because I have no accounts in collections or going into collections. And any accounts that may potentially do so, I would be contacted by the company themselves either by phone or letter. Not to mention, I checked the numbers of all my accounts that could go to collections and not a single one of them has an 866 number.

I refuse to answer numbers outside of my area code and so have to listen to the voicemails.
This number, the voicemail was left by an actual person (Diane or Diana Morgan I think) and it just said "Hi this is ____, the is a message for (my name). It is important that you call us back at (866 number)". They don't say who they are or anything.
The other number to watch out for is 423-933-1462. They leave an AUTOMATED message that says the exact same thing.

As for what NJ Dave said about it being a collector for Optimum Online, I don't have an account with Optimum Online. My internet account is with a different company and the one time that account almost went into collections, they sent me a letter saying what I owed by when or they would send it to collections.

It has been my experience that all companies you have accounts with inform you via letter before they send your account to collections. And they send you at least 2 letters before doing that. Simply because they lose money when they report your account to collections.

So I just googled this Sunrise Collections Agency that some people think these calls are coming from and they don't have an 866 number either! Plus all there numbers are out of NY so if it's not an 800 number, then the area code is 631.

I think I might email them and let them no that someone is contacting people on their "behalf" to collect on non existent debts.

Correction. They have one 866 number but it doesn't match the number they gave me.

According to another site like this, it's a number trying to collect on Avon Accounts but it sounds like it's not legit because most of the people contacted either have paid in full or haven't been an Avon representative in a while.

this phone number just called and it defently wasnt a credit service it sounded like some kids laughing and jokeing or something