The config below is a sample for configuring QoS on a Cisco router. The below config is good for 10 simultaneous calls on G.711 codec. This QoS setting is geared towards SHDSL/EoC/Fibre services with guaranteed bandwidth.
!
class-map match-any VoIP
match protocol h323
match protocol rtcp
match protocol rtp
match protocol sip
!
policy-map VOIPQoS
class VoIP
priority 2000
set dscp ef
class class-default
fair-queue
!
interface GigabitEthernet0/0
service-policy output VOIPQoS
!