[KLUG Members] Re: VoIP router choice

[Adam Tauno Williams]

> Does anyone know of a good T1 card that works with Linux?  

Both Digium and Cyclades make these cards. (Last I knew anyway).

> Will IPCop  work with the T1 card?

No idea.

> What exactly has to be done to do the VoIP on the Cisco router?  

Here is the relevant slices of a Cisco configuration,  the included interface is
a frame relay PVC (just for example of how to apply the QoS to the interface).

...
class-map match-all voice-256
  match access-group 100
  match ip precedence 5
...
policy-map voip-frame-256
  class voice-256
    priority 128
  class class-default
   fair-queue
...
!
interface Serial0/0:0.100 point-to-point
 description Monroe to 4565 Herman St
 bandwidth 256
 ip address 192.168.121.1 255.255.255.0
 frame-relay class voice256x128
 frame-relay interface-dlci 100
!
...
map-class frame-relay voice256x128
 no frame-relay adaptive-shaping
 frame-relay cir 256000
 frame-relay bc 1000
 frame-relay be 0
 frame-relay mincir 256000
 service-policy output voip-frame-256
 frame-relay fragment 320
!
...
access-list 100 permit udp any any range 28000 28255
access-list 100 permit tcp any any eq 7000

> What  will happen without it?  Will it work but degrade the sound? 

Oh, yea!  Without QoS VOIP is basically useless, at least for any application
where you NEED it to work ALL the time (like a regular phone).  If there is a
rise in the amount of data traffic on the circuit you'll get drop-outs, lost
calls, white noise (which can be DEAFENING!), clipping, etc... depending on how
loaded the circuit is and how your codec manages the loss of packets (the
ability to deal gracefully with packet loss varies immensely between packages &
devices, for physical handsets it is the usuall rule - what costs more works
better; software is the opposite, free packages work better than commerical
ones).