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PSTN-A --> VoIP --> PSTN-B Problem

cau
Level 1
Level 1

Hi,can anyone help me with my VoIP setup? I currently have two branches, Branch-A and Branch-B in two different cities. I'm trying to setup an infrastructure whereby I can call into my local Branch via PSTN into my Cisco voice gateway... go through the Internet.. routed to the other Branch and out the Cisco voice gateway to the remote PSTN. Here,s what it looks like.

PSTNA -> CiscoGW -> Internet -> CiscoGW ->PSTNB

Branch-A has a CiscoGW with 4 FXO ports connected to 1FLs and Branch-B CiscoGW has a NM-HDV(VWIC-1MFT-T1) connected to a T1 PRI. My problem is I can dial from PSTNB to Branch-B and out to PSTNA, it would ring but I get no voice. And when I say no voice I mean on either side.

By the way, I'm just using simple Dial-Peer statements to point from one site to the other. Using Codec G.711. I actually followed steps from this link below but I made it even simplier as I don't have SIP configured.

http://mit.edu/sip/sip.edu/ciscoGW.html

Thanks for your help!

24 Replies 24

venkekri
Level 1
Level 1

This is a pretty straight forward setup.

You have mention that you are able to make the far end phone ring, however when the person picks up the phone there is No Audio on either end.

That clearly states that the signalling is good but there is a trouble in RTP cut through.

You can intiate the following command.

voice rtp send-recv

voice call send-alert

On both the routers.

Also when both party have picked up, do a show call active voice brief, and check the status of the call legs. It should ideally show 'active'. However if shows 'connecting or connected' then we have issue.

Also to make sure your dial peers are correct, you can run "debug voice ccapi inout" on either routers. This will show that which dial peer is getting invoked and wat digits are being sent across.

Also check if the symptoms are same when you call from Pstn A--Branch A -- Branch B ---PSTN B.

I have similiar problem unable to send and receive calls.

Here is the call log from the gateway

Hin Lee
Cisco Employee
Cisco Employee

This is a better doc for what you are trying to achieve.

Configuring Connection Trunk for VoIP Gateways

http://www.cisco.com/en/US/tech/tk1077/technologies_configuration_example09186a00800afd65.shtml

Thanks for your quick responce.

But i am testing on only one site. I have no gatway at other end.

First i want to test at site A.

Following Things i got at site A

=> router 2620 register with CCM

=> 7940 IP Phone.

When i make a call bell is ringing but both person cannot hear each other.

If i understood correctly, your setup is as follows.

7940----ccm-----2620-----FXS---phone

From the logs you have attached, it seems that your gateway is registered with CCM as MGCP. If thats the case, it would be a good idea to bind the media with an interface. Check the below link.

http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/vvfax_c/callc_c/xgcp_c/mgcpcht7.htm

Hope that helps.Also clarify if my deduction of your gateway registered as mgcp is correct or not.

There are some known bugs on no audio issue. Check:

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_field_notice09186a00801c96bd.shtml

Also check the routing.

Thanks

Venky

1. Phone===2620===CCCM===7940

2. Yes you are right it registered as MGCP.

3. How do i check the routing

4. "it would be a good idea to bind the media with an interface" What is the purpose of bindind. Presently i am unable to make and receive call from IP phone.

Sorry i am new to cisco. Trying to learn IT Telephony. I would appreciate you could assist me.

Thanks

Can anyone reply to my question. IP Phone is ringing but unable to hear and make calls.

The caller can make call from pots phone but unable to hear from the receiver.

Please post you gateway config (sh run).

Firstly thank you for quick reply. Please open an attachment for gateway configuration.

Any Suggestions

mgcp call-agent 192.168.0.111 which means that your callmanager is 192.168.0.111

So that means that this is probably your issue

ip route 0.0.0.0 0.0.0.0 192.168.0.111

If your ccm is also your gateway, then that is also a problem because it cannot have two separate network connected.

Thanks for the reply.

So what should i do to work the things perfectly?

Hard to say. The reason is that I don't know how you have your network setup.

This line

ip route 0.0.0.0 0.0.0.0 192.168.0.111

should be

ip route 0.0.0.0 0.0.0.0 < ip-address-of-default-gateway for 192.168.0.x subnet >

Is this your config?

ip phone --> CCM --> MGCP Gateway () --> PSTN via FXO?

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