I have a wildlife tech caller with 26 sounds on it. My caller is 10+ years old [beeep]. the remote was hooked up to a walkie talkie, it has a horn type speaker, and the electronics were in a little plastic box. It takes batteries to run the external speaker horn, batteries to run the black box, and batteries to run the walkie talkie and remote. The sounds are awesome [beeep] but was told I could only upgrade the sounds from the company and no other sounds were supported. Last year it stopped working so I took it apart to fix it-and did fix it. I found the sounds were recorded wav files on a sd card.
don't know if that helps ya or not. I did not try and add new sounds to it but probably could of in the wav format.