You can look at the stream (RTP) information on the phone for an ongoing call to see what codec is in use.
In general there are no big differences between various phone models and the codecs they can support. However for newer codecs, like Opus, there are a distinct difference as this has to be supported by the phone model and older models of phones doesn’t usually do that. What codec the phone supports should be stated in documentation for each model. The recommendation would be to look through this.
Yes you can control what codec a device uses by regions and codec preference lists. This is outlined in documentation, I’d recommend that you read this.
G711 are supported by both old and new phones models but the codec like Opus will not be supports by old phone models.
The data sheet for the phones provides these information. Kindly go through the data sheets of your phone.
if your requirement is to see what codec is used during the call, you can see that from status>>call status.
