The PMP320 platform will eventually support all 5 WiMAX QoS profiles (BE, rtPS, nrtPS, ertPS, UGS) However, in the current version of software the ertPS QoS profile is not working.  The ertPS profile was introduced to WiMAX with the 802.16e profile (wasn't part of the 802.16d profile).  It is used as an efficient way to support VoIP connections and is an improvement over the rtPS and UGS profiles that previously existed.  It is especially effective in making the UL more efficient for VoIP conversations by not allocating bandwidth during silent periods. We are developing a plan to fix this feature but it may not be available until mid-year. Until the feature becomes available, the recommended alternative from engineering is to use UGS service flows for VoIP with CIR settings to dedicate the bandwidth per user voice channel.