According to the BLA draft https://tools.ietf.org/html/draft-anil-sipping-bla-03#section-6.2, when a phone attempts to seize a bridged line appearance (e.g. NOTIFY with state=trying) and another user has just seized the line, a 500 with Retry-After header should be returned to the requester. The phone should then wait the amount of time in the header before retrying another trying NOTIFY. However, what I'm seeing in practice is very different. I have a scenario where a 500 is returned with Retry-After=2, and the phone does not respect the header and immediately sends a NOTIFY with state=terminated for the same line-id, before attempting to seize another line appearance (e.g. x-line-id=1). This diverges from the spec entirely. Any ideas why?
The BLA phone config:
<entryreg.1.callsPerLineKey="1"/><entryreg.1.lineKeys="1"/><entryreg.1.strictLineSeize="1"/>Firmware 5.6.0