Switch port that connects to ISR acting as Voice GW

Hello community,

I came across an isse with an ISR acting as voice GW not being reachable even though the port where it connects is up and the "show cdp neighbor detail" displays both the ISR's name and IP address. I was looking at the configuration of the switch and the only thing that stands out as weird is the fact that it is configured as follows:

interface GigabitEthernet0/10
 description ISR Voice GW Router
 switchport access vlan 100
 switchport mode access
 switchport voice vlan 100
 srr-queue bandwidth share 1 30 35 5
 priority-queue out
 mls qos trust device cisco-phone
 mls qos trust cos
 spanning-tree portfast
 service-policy input SOME-POLICY
end

I have never seen a switch port to have the voice and access vlan match, is this a valid configuration? The voice VLAN is indeed VLAN 100 and there are multiple data VLANs (i.e. 50, 180, 200, etc).

How do you usually configure a switch port connected to an ISR acting as a voice gateway? Do yo just configure the "switchport voice vlan x" and not the access one? In that case, would the access VLAN stay with VLAN 1?

Thanks in advance for your input