[Radiowilbur]

Can anyone identify this mic?  or is it a speaker?  It has a three wire cord.  Bottom number is: 28-7324.  

[KCMike]

I can't say for sure but found this one that's similar.
http://www.ebay.com/itm/Vtg-1930s-PHILCO...SwknJX0ukR

[Ron Ramirez]

Hi Wilbur

It could be either a microphone or a speaker, really.

These were used with Philco Beam of Light radio-phonographs that had the record cutter attachment as a microphone.

They were also used with Philcophone intercoms of the same period as a combination microphone and speaker.

[Radiowilbur]

excellent, thanks for the info..... i don't need it, i will probably list it on e bay. it has three wires, i will try to test it first.