I have had a simular situation to a number of other people. They call at least twice a day and when I answer there is no one there...
Extremely frustrating.

I am overseas and worried about getting charged for the call(s)

I'm in the same boat, and receive calls to my mobile from this number at least twice a day....how do we stop this pest?

Keep on getting hang up message from this number- surely they shouldn't be allowed to ring if number is on Do Not Call Register.

They ring every day at 4.50 pm, when you ring this number back you are put on hold waiting for them to do a union survey so you are paying for the phone call to Sydney. Big scam, union should look after their members, not try to scam them.

They are getting desperate because Julia Gizzard is frantically searching for new info which will be USED as brain washing lies tricking you into voting for Labor again.

Just recently resigned United Voice (Union) and apparently this is how this business got my details - the name of THIS business is "Customers 1 to 1" - I got a "hang up" call from the number and after checking the details here - returned their call to probe for more info - upon giving her my name, she looked it up and told me that United Voice had given them my details.

Repeatedly keep ringing my phone. They don't leave a message.

have had MANY missed calls from this number. Will NOT be ringing back after reading these messages. Does anybody know how I can stop these people ringing me?

Oh boy! I cannot wait to they call back so I can give them a ear full!!! Hahaha

rang my mobile, husbands mobile and land line at exactly same time...answered one, no one on other end...exact same time next day, didn't answer, went o message on mobile...someone asking for me by name but no actual message or ID

OMG - have had over 20 calls in one week from these people bot on mobile and home phone - get the message - NOT INTERESTED

A guy named John keeps calling me from this number I don't answer but he leaves me voice messages. Please Stop.

has rang few times no answer when i answer or ring back

i received 11 calls from this number! how can i stop receive this call?

Missed their calls from the 21st May, 22nd May, 27th and 28th. I have been at work and unable to answer. No message left

returned call.
they claimed to be the australian union of trade unions (AUTU) doing a national survey of union members. I am not a member of their affiliated unions and their questions were not legitimate. Potentially these people were information farming.
it is suggested to not leave personal information

Am located in Perth, two missed calls on my mobile around 6pm. No message left. Will not return call.

Same. Calls but won't leave message. I won't answer at all.

Still continuing to ring (6 times) and now are using a different number (02) 6253 2149.