Technically yes, but since the SPA phones are older (and now moving towards obsolete) models you likely will not get the benefit of the higher performing and newer electronics in the SPA 500 series handsets. If you have some older SPA handsets lying around you could test it out and see if you or your customer is happy with the results or not but my guess is you may not be.
I'm asking specifically about the handset, not the entire phone. I have a SPA525G that looks like someone swapped the handset with a SPA900 series phone. The handset falls off the cradle. Based on the size of the cradle, it looks like the mouthpiece is smaller on a SPA900 series phone versus a SPA525G. Can you confirm whether this is true?
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