Connecting the IP phone to a switch port may have configuration issues; here are some of the common configuration issues encountered by network engineers when connecting an IP phone to a switch port:
1. Voice traffic may not be configured.
2. Data traffic may not be configured.
3. Both voice traffic and data traffic are not configured.
4. Inline power support may have been overlooked.
5. QoS may not be configured properly.
6. QoS may not be configured on the Layer 2 Uplink.
7. QoS may not be configured on the Layer 3 Uplink.
8. This is the most common issue encountered; all issues above may have been met but if this one is not addressed, the switch will not respond properly: Cisco predefined macro is not used to configure the switch.