Why DSCP configuration is not taking effect for voice based SSID in IAP ?
For the Voice SSID type, the WMM DSCP mapping doesn't work, this is how it has been designed. The WMM DSCP mapping only works on Employee SSID type.
By default, Instant supports the ALGs for all common protocols SIP, SVP, Vocera, Cisco Skinny, Alcatel NOE. Traffic that is identified as voice (these protocols) is put in voice queue automatically.
All we need to make sure is the type of network we create on the IAP and make sure it is configured as "Voice", so this way we prioritize the voice traffic by default.