VOIP: I cannot be heard by remote users

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Jan 6th, 2009
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Hi all,

I manage a network whereby the branches are connected with VOIP using pots connected to local PABX. All has been well till yesterday when one branch cannot hear callers from the central site. I have tried checking all that i know of VOIP but in vain. Please, i need someone to point me in the right direction.


My background is routing and switching.


"What would make the remote users fail to hear me. I can hear them clearly"

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jason.dolan Tue, 01/06/2009 - 06:12
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In my experience the only time I had this happen is when the Voip phones had somehow gotten an IP that was on the data side of the network instead of in the voice vlan where it belonged. This caused the user to only get audio in one direction.

njorosam Tue, 01/06/2009 - 06:57
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I'm actually not using VOIP phones. I am using analogue pots connected to local PABX and remote PABX. Normal landline calls are OK currently.

davidjani Tue, 01/06/2009 - 08:50
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May be worth checking that nobody has messed about with your routing.


I assume that you have done this considering the R&S background but it is very easy to think its something to do with voice, thus overlooking the foundation that the voice requires to run over.


Definitely have route both ways for Voice VLANs? No new access lists blocking Voice subnet for the return leg etc etc....?

njorosam Wed, 01/07/2009 - 03:27
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output from "show call active voice brief" both from the gw and the remote site:



VOIP-GW#show call active voice brief


: hs. + pid:


dur hh:mm:ss tx:/ rx:/


IP : rtt:ms pl:/ms lost://


delay://ms


media inactive detected: media cntrl rcvd: timestamp:


MODEMPASS buf:/ loss /


last s dur:/s


FR [int dlci cid] vad: dtmf: seq:


(payload size)


ATM [int vpi/vci cid] vad: dtmf: seq:


(payload size)


Tele (callID) [channel_id] tx://ms noise: acom: i/o:/ dBm


MODEMRELAY info:// xid:/ total://


speeds(bps): local / remote /


Proxy :,,,,, endpt: /


bw: / codec: /


tx: /,/,/


rx: /,/,/






Telephony call-legs: 1


SIP call-legs: 0


H323 call-legs: 1


Call agent controlled call-legs: 0


SCCP call-legs: 0


Multicast call-legs: 0


Total call-legs: 2


3E7C : 94603 434299274ms.1 +13050 pid:3000 Answer 203293153 active


dur 00:00:03 tx:424/11815 rx:427/8377


Tele 0/3/0:15 (94603) [0/3/0.10] tx:16190/8440/0ms g729r8 noise:-84 acom:45 i/0:-49/-74 dBm




3E7C : 94604 434299274ms.2 +13040 pid:1000 Originate 52 active


dur 00:00:03 tx:427/8377 rx:424/8423


IP 10.206.124.253:16704 SRTP: off rtt:0ms pl:6850/20ms lost:1/1/0 delay:60/60/70ms g729r8


media inactive detected:n media contrl rcvd:n/a timestamp:n/a


Telephony call-legs: 1


SIP call-legs: 0


H323 call-legs: 1


Call agent controlled call-legs: 0


SCCP call-legs: 0


Multicast call-legs: 0


Total call-legs: 2




VOIP-GW#




052R#show call active voice brief


: hs. + pid:


dur hh:mm:ss tx:/ rx:/


IP : rtt:ms pl:/ms lost://


delay://ms


media inactive detected: media cntrl rcvd: timestamp:


MODEMPASS buf:/ loss /


last s dur:/s


FR [int dlci cid] vad: dtmf: seq:


(payload size)


ATM [int vpi/vci cid] vad: dtmf: seq:


(payload size)


Tele (callID) [channel_id] tx://ms noise: acom: i/o:/ dBm


MODEMRELAY info:// xid:/ total://


speeds(bps): local / remote /


Proxy :,,,,, endpt: /


bw: / codec: /


tx: /,/,/


rx: /,/,/






Telephony call-legs: 1


SIP call-legs: 0


H323 call-legs: 1


MGCP call-legs: 0


Multicast call-legs: 0


Total call-legs: 2


3E97 : 6063 796032798hs.1 +1692 pid:1000 Answer 203293318 active


dur 00:00:14 tx:546/10767 rx:290/5743


IP 172.31.113.111:18042 rtt:34ms pl:0/0ms lost:1/0/0 delay:70/260/10ms g729r8


media inactive detected:n media contrl rcvd:n/a timestamp:n/a


3E97 : 6064 796032799hs.1 +1690 pid:200 Originate 52 active


dur 00:00:14 tx:297/5883 rx:546/10767


Tele 0/3/1 (6064) [0/3/1] tx:31840/10830/0ms g729r8 noise:-55 acom:6 i/0:-56/-79 dBm




Telephony call-legs: 1


SIP call-legs: 0


H323 call-legs: 1


MGCP call-legs: 0


Multicast call-legs: 0


Total call-legs: 2




052R#

njorosam Wed, 01/07/2009 - 03:28
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Previous post is a command output from both remote and cetral site:


I've treied to figure out what the issue could be in vain. Based at the HQ where the gw is located, i can hear the voice from the remote site, but they cannot hear me. If a call is orinated either from HQ or remote site, the results are the same. The voice gateway has only one ethernet interface and terminates other 31 sites which are working OK. The remote site has multiple interfaces and has been working till last saturday when it failed. Can't quite figure out whta could have changed at that time...if any.


Nicholas Matthews Wed, 01/07/2009 - 08:29
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From the output it looks like analog problems - either you're not getting audio or possible DSP problems.


You can start by reloading the gateways to see if this temporarily restores audio.


hth,

nick

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