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Basic VoIP with FXS ports across the router

Heloo

I am running a pilot before implementing basic VoIP with leased link between two location having 2621 routers.

IN the lab

- I have one 3660 and one 2621 connected back to back with ethernet interface . IOS is 10.0.5 (T)

- has FXS voice cards with one telephone on each.

Problem:

- I am getting clear voice when communicating between the two FXS ports on the same router.

- But i can't hear any voice if i try to communicate across the two router's FXS ports. Although i do get the ring. There is lot of noice and disturbance

I am sure this can be fix... as there should not be problem between two routers connected back to back.

- Pl some one can suggest fine tuning of the config. (at present i hv just basic config defining the dial-peers and with pots and Voip.

Thanks in advance

Rakesh

9 REPLIES
New Member

Re: Basic VoIP with FXS ports across the router

Rakesh,

This sounds like a codec issue, can you post your configs, and I'll work this through with you.

Spike

New Member

Re: Basic VoIP with FXS ports across the router

thanks spike... my config is like below..

voice-port 2/0/0

!

voice-port 2/0/1

!

!

dial-peer voice 201 pots

destination-pattern +2001

port 2/0/0

!

dial-peer voice 202 pots

destination-pattern +2002

port 2/0/1

!

dial-peer voice 601 voip

destination-pattern +1001

session target ipv4:10.250.0.2

!

!

interface FastEthernet0/0

ip address 10.250.0.1 255.255.255.0

no ip redirects

no keepalive

duplex auto

speed auto

no cdp enable

** the similar config is on ther other router.

pl. advice..

Thanks and regards

Rakesh

======

New Member

Re: Basic VoIP with FXS ports across the router

Rakesh,

Remove the "+" from the destination patterns it only confuses matters.

>

Confirm you have the same codecs configured at each end, either by re-typing them in

>

dial-peer voice 100 voip

destination-pattern 1001

codec g729ar8 (for compressed calls)or

codec g711ulaw (for uncompressed)

>

or verify them by doing

>

SHOW DIAL-PEER VOICE

>

>

Cheers

Spike

New Member

Re: Basic VoIP with FXS ports across the router

Hey Spike

It worked...! thanks..the quality is v.GOOd now.

Pl. give ur guidence for my real-life scenario -

- I hv to do VOIP between the two router (diffent locations) which passes the network wich 3 hops having one T1 link and one IPLC link. The total round trip time (ping response) is about 695ms.

- We are not expecting very high quality voice.. but aiming for reasonably good voice communication.

It would be great if you can give some TIPs and some DOs and DON'Ts.

regds

Rakesh

======

New Member

Re: Basic VoIP with FXS ports across the router

Rakesh,

Use a low bandwidth codec (g729ar8) for the VOIP dial-peers, then use RSVP to reserve bandwidth along the wan links. The round-trip delay shouldn't cause you too many problems, however jitter will (variance of round-trip) Are you running data over these links as well as the voice ? What are the routers and performance capabilities (ie Model no., amount of RAM etc). Remember quality of service mechanisms only need consideration if WAN Routers need to queue packets (ie WAN link congestion). Try it, and see !

>

Spike

New Member

Re: Basic VoIP with FXS ports across the router

make sure the codec sttings match on the voip dial peers pointing at either router. you should be straight after that. If not, we need a sample of your config

New Member

Re: Basic VoIP with FXS ports across the router

thanks for the reply.. my config is attached on the previous sesstion..

regds

New Member

Re: Basic VoIP with FXS ports across the router

Msamuels is definetely right. if that doesn't work, you will have to show us the details about each particular voip dial peers by issuing:

show dial-p voice 601

also it will be useful if you gave us the output of the command "show dial-p voice sum" just so that we can rule certain things out.

rgds,

E

New Member

Re: Basic VoIP with FXS ports across the router

If the call establishes after going off hook and you have bad speech quality, or just one way speech - then you are probably missing "ip routing" on one or both of the routers. You require this config even if you don't intend to use a routing protocol. If it's not there you will have variable speech quality what ever codec is used - why is this so? it's just one of those things in IOS!!!!

Good luck... Phil.C

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