First a Random Sight Survey should be done.VoIP is supported only in the Cisco Aironet 1400 Series Wireless Bridge .The default value for maximum retries is 3 for the Low Latency setting.Note You may also configure the CoS 4 (Controlled Load) user priority and its maximum retries value. For more information in configuring VoIP feature refer the following site
1400 is an 802.11a bridge, so VoIP is supported on more access point platforms (1000,1100,1200,1300). Not sure which VoIP handset you are using, but the "STREAM" feature is intended to reduce the # of re-transmissions for a single packet (i.e. RTP). If enabled, would need to ensure that only RTP is getting put into this queue, otherwise could have some stability issues. For instance, the Cisco AP puts all Cisco 7920 packets into the CoS 6 queue via CDP recognition regardless of present qos policies.
Do not want to reduce transmissions for SCCP, etc.