Here is the link for configuring the 3550 with Priority-Tagged Frames. Above configuration is correct with the exception of the QoS in the below link. Also as a precaution I usually turn on Portfast BPDUguard on all portfast ports to insure I have no rogue switches plug in.
I'm kinda lost with what you are trying to achieve but I'm gonna throw out my thoughts.
1. When configured with switchport access command and switchport voice command, dot1q and dot1p should work in tandem. Phones will tag COS 3 & 5 based off CM configuration and will be trusted by the switchport with the appropriate command. Access port will mark down to 0. Policy-maps can be used on the 3550 to match and set traffic from the PC. See QoS SRND. link below.
2. If your goal is to have PC & Voice on the same vlan then possible try this. Create a trunk port on switch. Native vlan will be 1. Prune or restrict only 1 vlan (or different native if allowed). See if both PC and Voice will come over on the single vlan. Alternatively set the native vlan to 100. Not sure if 3550 allows change of Native vlan. Apply trust cos statement to trunk port. I know for a fact that an Ip phone will come up on a trunk port but I've never really researched much into how the vlans ultimately were configured as it was a lab test awhile back.
I'm not able to access my old voice mail messages all of a sudden. The recording says something like 'the message is currently not available'. This has never happened before in all the years I have been using this system. I have t...