Sim Card with Ebay phone still working? Who gets charged?

[iMore Question]

I just recently bought a replacement cell phone off of ebay and it came with two sim cards. The owner of the phone said he was switching from Verizon to Tmobile so he couldn't use his phone on their service. I recently discovered that the sim card he gave me still works on my old phone. It has a different phone number, but I can text and make calls. What I'm wondering is how or when will Verizon deactivate that sim card or if I use it, will that original owner get charged? Does anyone have any info on this? I haven't used it other than just to send some test text's to see if it worked.

 

[kataran]

It's obvious that the Sim belongs to the Seller and doing the right thing by contacting him that he accidentally left his Sim behind would be the proper thing to do