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VoIP QOS questions

Im currently testing VoIP (back to back). Router to router using FXS. This works fine. I want to use QoS and bandwidth reservations.

We are currenlty using DSP Modules -8-Channel Packet Voice DSP Module and from my understanding that means 8 simulataneous calls/fax can go throuhg the router.

Since Im using Cisco equipments I just need a few clarification and Cisco recommendation on QoS.

1. What is the minimum bandwidth a call will take ? This will help configure my reservation protocol

2. I got a 1Meg lease line (1,024Kbps). How much should I reserve for Voice traffic ?

3. Im also will test FXS to FXO (connected to PABX) and will configure Hookflash Relay. To confugire timing hookflash-in and out what is the recommended msec to be used ?

I hope someone will help

1 ACCEPTED SOLUTION

Accepted Solutions
Silver

Re: VoIP QOS questions

please post configs and SH VER from both routers - thanks

5 REPLIES
Silver

Re: VoIP QOS questions

Answers in line -

1. What is the minimum bandwidth a call will take ? This will help configure my reservation protocol

Depends on the codec used. Refer here for more information -

http://www.cisco.com/warp/public/788/pkt-voice-general/bwidth_consume.html

2. I got a 1Meg lease line (1,024Kbps). How much should I reserve for Voice traffic ?

Depends on the codec used, as above. You don't necessarily need to reserve any bandwidth, the critical thing is the prioritisation of the voice traffic over other traffic. Refer here for more information -

http://www.cisco.com/warp/public/788/voip/voip_ppp_highbw_rtp_prio.html

3. Im also will test FXS to FXO (connected to PABX) and will configure Hookflash Relay. To confugire timing hookflash-in and out what is the recommended msec to be used ?

Depends on what the PBX or central office is expecting. Refer here for more information -

http://www.cisco.com/warp/public/788/signalling/pbx_across_ip.html

New Member

Re: VoIP QOS questions

Thank you for all the informative links. Quite helpful. I follow the example on cofiguring FXS to PABX via FXO. I manage to make a call from a phone attached to the PABX to a phone attached to the FXS card on the other end. However when I want to make a call from the phone on the FXS; when I pick up the handset, it gives me a disconnection tone.

I can send the config if you want. Setup is as follows:

phone<-->PABX<-->Router(FXO)<---lease line--->Router(FXS)<-->phone

New Member

Re: VoIP QOS questions

Could it be that the hookflash timing I set on the voice ports is different from the Handset and PABX ?

I really need help

regards

Silver

Re: VoIP QOS questions

please post configs and SH VER from both routers - thanks

New Member

Re: VoIP QOS questions

I couldnt post it as the characters exceeds the limit. I can send it as attachments in text file

Let me know

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