I'm sorry if this has already been addressed, but I couldn't find an answer to my question.
I have a pretty standard setup: a few subinterfaces on a router connected to a trunk port on a switch (G0/24). All other ports on the switch have an access VLAN as well as a voice VLAN. However, I apparently fat-fingered the configuration and left G0/24 as an access port. I didn't notice because my phone still registered with the distant end CUCM. How did this happen if G0/24 was not configured as a trunk port?
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G0/24 had a voice vlan and access vlan configured. The registration went through just fine - I was even able to dial out. Unfortunately, I didn't think to collect logs before I changed G0/24 to a trunk port as originally intended.
No, G0/24 was set only as an access port:
switchport mode access switchport access vlan 49 switchport voice vlan 48
When I realized the error, I defaulted G0/24 and changed it to:
switchport trunk encapsulation dot1q switchport mode trunk
Yeah, I think i'll need to recreate the situation and do a packet capture. I know access ports process tagged voice packets, but I didn't think they transmitted tagged packets. I suppose they need to for a Cisco phone to know what vlan is the voice vlan.