I'm familiar that WA state is a 2-party consent state for the recording of telephone calls but what is the correct way to make notification of recording when there is only a pre-recorded message on the other end?

My situation is this:

1- A collection agency is attempting to collect a debt that is not mine. (I suspect they know it's not mine as they haven't bothered to make any hard inquiries or place collections notices on my credit report.)

2- I am located in Washington state, said CA is located in South Carolina.

3 - I have instructed (via certified mail, return receipt) that all communication with me is to occur in writing via post only. (I failed to note, in my letter, that I intended to record phone calls.)

4 - I periodically receive telephone "collection" calls from said CA but only with pre-recorded messages.

I would like to tape one of these calls but how do I meet the two-party notification requirement on a pre-recorded phone call? Do I simply announce I am taping the call to the recording that is on the other end of the phone, knowing - as I do - a human will not be there to hear my announcement?