VLAN Management
Voice VLAN
229 Cisco 500 Series Stackable Managed Switch Administration Guide Release 1.3
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There may or may not be separate voice and data VLANs. The phones and 
VoIP endpoints register with an on-premise IP PBX.
• IP Centrex/ITSP hosted: Cisco CP-79xx, SPA5xx phones and SPA8800 
endpoints support this deployment model. For this model, the VLAN used 
by the phones is determined by the network configuration. There may or 
may not be separate voice and data VLANs. The phones and VoIP 
endpoints register with an off-premise SIP proxy in “the cloud”. 
From a VLAN perspective, the above models operate in both VLAN-aware and 
VLAN-unaware environments. In the VLAN-aware environment, the voice VLAN is 
one of the many VLANs configured in an installation. The VLAN-unaware scenario 
is equivalent to a VLAN-aware environment with only one VLAN.
The device always operates as a VLAN-aware switch.
The device supports a single voice VLAN. By default, the voice VLAN is VLAN 1. 
The voice VLAN is defaulted to VLAN 1. A different voice VLAN can be manually 
configured.   It can also be dynamically learned when Auto Voice VLAN is enabled.
Ports can be manually added to the voice VLAN by using basic VLAN 
configuration described in the Configuring VLAN Interface Setting section, or by 
manually applying voice-related Smartport macro to the ports.   Alternatively, they 
can be added dynamically if the device is in Telephony OUI mode, or has Auto 
Smartports enabled.
Dynamic Voice VLAN Modes
The device supports two dynamic voice VLAN modes: Telephony OUI 
(Organization Unique Identifier) mode and Auto Voice VLAN mode. The two 
modes affect how voice VLAN and/or voice VLAN port memberships are 
configured. The two modes are mutually exclusive to each other.
• Telephony OUI
In Telephony OUI mode, the voice VLAN must be a manually-configured 
VLAN, and cannot be the default VLAN.
When the device is in Telephony OUI mode and a port is manually 
configured as a candidate to join the voice VLAN, the device dynamically 
adds the port to the voice VLAN if it receives a packet with a source MAC 
address matching to one of the configured telephony OUIs.   An OUI is the 
first three bytes of an Ethernet MAC address.   For more information about 
Telephony OUI, see Configuring Telephony OUI.