to bring this to a conclusion using a VVX1500 or a VVX 601 the BLF process outlined => here <= shows the BLF on a VVX 1500 (or VVX 601) as follows:
Busy or Alerting state
RFC 4662 support was added by Digium / Asterisk => here <=
Polycom addressed an issue in VOIP-119610 where a phone would crash SUBSCRIBING to a attendant.uri.
Support for RFC 4662 was added by Polycom back in 2009 via VOIP-42091 and focuses mainly on our Partner Broadsoft.
Any change to the above would require a feature request as explained in detail => here <=
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