Other Party’s Insurance Not Able to Reach Witness or Insurer

Recently got into a fender bender a few weeks ago and the claim is still being investigated. At the time of the accident, a ATT service technician gave me their business card because he witnessed me not being at fault.

Last week, I got a call from the other drivers insurance company telling me that they haven’t been able to get a hold of the witness because their number is out of service. They also haven’t been able to get a hold of their insured driver that ran into me too.

So, is it my responsibility to try to get a hold of the witness? Or do I just sit and wait until I get another update?

This is my first time being into an accident and going through this process so I’m still a little lost on what I should be doing!