Pre-Call Admission Control; Roaming Admission Control - Cisco 7925G Deployment Manual

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The dynamic minimum PHY rate is useful for deployments that require higher capacity where 24 Mbps and higher data rates
are only enabled. For this high capacity deployment configuration and with release 1.3(3), the minimum PHY rate would be
adjusted to 24 Mbps automatically even if the phone is configured statically for a minimum PHY rate of 12 Mbps. In releases
prior to 1.3(3), the minimum PHY rate would have to be changed to 24 Mbps manually from the default of 12 Mbps in order for
CAC to work correctly for this deployment configuration.
If an 802.11b AP is used, the highest available date rate would be 11 Mbps, so 12 Mbps can not be used as the minimum PHY
rate. For this 802.11b (11 Mbps) deployment configuration and with release 1.3(3), the minimum PHY rate would be adjusted
to 11 Mbps automatically even if the phone is configured statically for a minimum PHY rate of 12 Mbps. In releases prior to
1.3(3), the minimum PHY rate would have to be changed to 11 Mbps manually from the default of 12 Mbps in order for CAC
to work correctly for this deployment configuration.
TSPEC has precedence over QoS Basic Service Set (QBSS). QBSS is primarily used for roaming decisions if the channel gets
busy.

Pre-Call Admission Control

If Call Admission Control (TSPEC) is enabled on the access point, the Cisco Unified Wireless IP Phone 7925G sends an Add
Traffic Stream (ADDTS) to the access point to request bandwidth in order to place or receive a call. If the AP sends an ADDTS
successful message then the Cisco Unified Wireless IP Phone 7925G establishes the call. If the call is rejected by the access
point and the wireless IP phone has no other access point to roam to, then phone displays "Network Busy".
Cisco Unified
Communications
Manager
VoIP
Call Setup

Roaming Admission Control

During a call, the Cisco Unified Wireless IP Phone 7925G measures Received Signal Strength Indicator (RSSI), QoS Basic
Service Set (QBSS), and Packet Error Rate (PER) values for the current and all available access points to make roaming
decisions.
If the original access point where the call was established had Call Admission Control (TSPEC) enabled, then the wireless IP
phone will send an ADDTS request during the roam to the new access point.
Cisco Unified Wireless IP Phone 7925G Deployment Guide
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