Hi,

Snippet from a Cisco 877 config with QOS

class-map match-all VOICE-CONTROL
  description Voice Packets
match access-group 103
!
!

class-map match-all VOICE
  description Voice Packets
match access-group 102

!
!

policy-map WAN
  class VOICE
  priority 500
  class VOICE-CONTROL
  bandwidth 20
!

!
!
interface Vlan1
ip address 192.168.30.1 255.255.255.240
ip virtual-reassembly
ip tcp adjust-mss 1452
service-policy output WAN
!
interface Dialer1
service-policy output WAN

!

access-list 102 permit ip any any precedence critical
access-list 102 permit ip any any tos 5
access-list 102 permit udp any any range 16384 32767
access-list 102 permit tcp any eq 7000 any
access-list 102 permit ip any any tos 3
access-list 103 permit ip any any tos 3
access-list 103 permit ip any any precedence flash
access-list 103 permit tcp any any eq 1720
access-list 103 permit tcp any any range 2000 2002
access-list 103 permit tcp any eq 1720 any