I had issues with this firmware on a NV644 and I know it was removed for most models.
My guess is that there was a problem with that build.
I was working with Adtran Support a couple weeks ago and asked why A5.03 was never released for the 900e's and they said there were known issues with it, they recommended that I use R10.3.1. So far so good with R10.3.1 on both 900 and 900e.
ADTRAN removed the A5.03.00 firmware from the website because of numerous customer initiated technical support calls due to an issue that existed in that version of code. We did provide a notice of this issue in the A5.03 release notes, but enough customers still reported the issue so we decided to remove it from the website.
The A5.03.00 release notes stated:
Notice of Issue with RFC 3264 Media On Hold Method
If the ADTRAN unit receives an SDP offer with the RFC 3264 sendonly attribute to place the call on hold, it will not begin sending RTP again when a sendrecv attribute is received to remove the call from hold.
If you do not place calls on hold using RFC 3264, then you will not see this issue.
Please, let me know if you have any additional questions. I will be happy to assist you in any way we can.
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