I am using the HAP version 4.9 and my client using 4.5, i sent him the E3A file with current version which he couldn't open, can you please explain me how i can save my current version file to lower version file and send to them?
I assume using HAP requires subscription. You should ask the Carrier support.
Some software can't "downgrade". 2 reasons: they want everyone to be on subscription ($$$$$!), second, new features may get screwed up when you save to lower version.