Switchport access.
DHCP gives the phone its own IP address. If the phone is getting the IP address, then the IP Helper is working and DHCP is working.
The phone also needs the IP address of the voice server/gateway (they *really* shouldn't be calling it a "switch") which it needs to get from DHCP, but if it isn't getting it, either you're using the wrong Option, or you've formatted the entry wrongly.