h323-gateway voip interface

Unanswered Question
Apr 20th, 2011

I've read Cisco IOS command reference, but I'm still not sure about the purpose of "h323-gateway voip interface" command.

Moreover, I was trying to understand the difference between "h323-gateway voip interface" and "h323-gateway voip bind srcaddr".

Here's my config on the gateway router:

interface Fa0/0

  ip address
  h323-gateway voip bind srcaddr

interface loopback0

  ip address

  h323-gateway voip interface
  h323-gateway voip id GK ipaddr
  h323-gateway voip h323-id CUCME
  h323-gateway voip tech-prefix 408

From my understanding, the "h323-gateway voip interface" command should dictate the source address that being used to communicate with gatekeeper.  i.e. it should be (loopback0)

However, when I do a "show gatekeeper endpoint" command on the gatekeeper router, it's showing the RAS address as (Fa0/0).  How can I make the gateway router to use loopback0 communicate with GK, while using the Fa0/0 interface communicate with other H323 peers (such as CUCM)?

GK#show gatekeeper endpoint
CallSignalAddr  Port  RASSignalAddr   Port  Zone Name         Type    Flags
--------------- ----- --------------- ----- ---------         ----    -----  1720  60745 GK                VOIP-GW
    H323-ID: CUCME
    Voice Capacity Max.=  Avail.=  Current.= 0
Total number of active registrations = 1


  • IOS image being used is c3825-adventerprisek9_ivs-mz.124-24.T4.bin
  • I also tried making the gateway router a "H323-GW" instead of "VOIP-GW" by adding "allow h323 to h323" command.  Same behavior.



I have this problem too.
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Amer rajai Sha'er Wed, 04/20/2011 - 07:03


As i am sure you know , if you want this to happen , the loopback interface must have access to the GK IP ??

delete this command from the interface f0/0

h323-gateway voip bind srcaddr

and add this to the loopback :

h323-gateway voip bind srcaddr

Also add the h323-gateway voip interface on the interface f0/0 and give it a shot.


michael-luo Wed, 04/20/2011 - 08:45

Hi Amer,

Thank you for your reply.

1) Could you further explain what's the purpose of "h323-gateway voip interface"?

2) How is "h323-gateway voip interface" different with "h323-gateway voip bind srcaddr"?

3) If we have "h323-gateway voip interface" configured under multiple interfaces, what's the effect of that? (I guess this one is part of question 1 above).



Amer rajai Sha'er Wed, 04/20/2011 - 09:26


h323-gateway voip  interface Tells the router that this interface should be enabled for  H.323 packet processing.

h323-gateway voip id Identifies the ID of the gatekeeper.

h323-gateway voip  h323-id Configures the ID of this router. When the router registers with  the gatekeeper, the gatekeeper recognizes the gateway by this  ID.

h323-gateway voip tech-prefix  1# Registers a technology prefix

h323-gateway voip bind srcaddr Sets the source address of H.323 packets


michael-luo Wed, 04/20/2011 - 09:58

Hi Amer,

Sorry for stupid questions.

You said:

h323-gateway voip  interface Tells the router that this interface should be enabled for  H.323 packet processing.

h323-gateway voip bind srcaddr Sets the source address of H.323 packets

Why we need two separate command to enable the interface and set the source address?  The only reason I can think about is to have these two command in two different places (interfaces)

This doesn't make sense to me.  For example, you enable the H.323 packet processing on interface A but want the source address to be interface B?  Why you want to do that?

If you should use these two command in the same interface, why we need two separate command?



Amer rajai Sha'er Wed, 04/20/2011 - 10:09

Hello Michael,

It's not a stupid question , it's great question and i don't have the answer for it , i never thought about it before.

But from where i know , these two must be configured on the interface , even if you want to communicate with CUCM to let the gateway be a H.323 gateway.

One of my collegues once told me that he tried to do the config without the h.323-gateway voip interface and it worked , honestly i never tried it.


clileikis Wed, 04/20/2011 - 10:28

I'm curious about this as well.  Never needed the h323-gateway voip interface command to register my h323 gateways to Call Manager, only needed the h323-gateway source address command.  Not sure if the h323-gateway voip interface is only required for gatekeeper registrations..

michael-luo Wed, 04/20/2011 - 10:33

From my understanding, the "h323-gateway voip interface" is only required when registering with GateKeeper.

You cannot configure H323-ID and ID without this command.


Amer rajai Sha'er Wed, 04/20/2011 - 15:32

Hello Micheal,

Yes, you are right , the ID is tight to the voice interface but as of signaling it is not required , i test it on my lab for H.323 gateway for CUCM , it's working without the voip interface , it is only needed to communicate with gatekeeper.


Monica kumari Wed, 07/08/2015 - 01:21

I Still have doubt what if i have two CME's connected directly. i have bind loopback interface on both CME's but i can make call from site only but not from other side.

Facing One Way Voice Issues.

How does h323-gateway voip bind srcaddr works?why we get One Way Voice Issues?

How Does RTP works?

In my scenario on both cme routers i have bind loopback interface (Hq nad Br but in Hq site in dial peers i have taken session target ipv4:(ip address of serial interface) and in other site i have taken the bind loopback of hq i.e

i am able to call one site but not from other. and why on both sites in dial peers we have  to take take bind loopback ip address.

Please clear my concept.

Vivek Batra Wed, 07/08/2015 - 03:22
You must specify h323-gateway voip bind srcaddr command under desired interface else depends on call scenario, signaling and media may source from different interface and you may end up with one way speech issue.
Very old bug related to problem you are facing CSCdw69681.
If is the loopback address of HQ and is the loopback address of BR router, then you should have following configuration;
             In HQ router;
              interface loopback 0
                h323-gateway voip bind srcaddr
             In BR router;
              interface loopback 0
                h323-gateway voip bind srcaddr
HQ CME should have session target command pointed to whereas BR CME should have session target command pointed to 
elrayah99 Wed, 08/22/2012 - 10:46


h323-gateway voip interface    >> GW to gatekeepr communication.

- It is used to source RAS packets when communicating with a gatekeeper

h323-gateway bind srcaddr x.x.x.x >> GW to GW (CUCM) communication.

- It is not needed when you confgure the gateway to communicate only with a gatekeeper.

- It is used to source H.225 packets from the gateway.

- It is the same IP address defined when you add a gateway to a CUCM.

- CUCM does not repspond to undefined H225 packets

Thank you,


omerpal1190 Mon, 07/11/2011 - 04:46

One site is running CME itself. sO it has already one h323 interface. If i want to to connect that gateway with CUCM,i need to put one more h323-gateway voip bind srcaddr X.X.X.X command.

But i am gettting below error whenever i put h323-gateway voip bind srcaddr X.X.X.Xcommand under loopback interface.

"Bind IP Address configured. Please remove before reconfiguring"

Hythim Ali El Hadad Mon, 07/11/2011 - 06:05

you have this command under another interface

the Router tell you to remove it first that you can't source your h323 pkts with 2 different IP addresses using this command

this is the adv. of this command

omerpal1190 Mon, 07/11/2011 - 06:51

I cant remove it, since this router acting as cme is connected with othwe cme too.

vandana Mon, 07/11/2011 - 07:22

You don't need this cmd if call is coming from another CME. You don't registered this as h323 GW to CME.

iptuser55 Tue, 07/12/2011 - 06:05

Just to add, I always thought the "h323-gateway voip bind srcaddr X.X.X.X" commend was to tell the destination where the IP packets came from particular if you have loopback address otherwise you can have one way transmission , loss of packets etc


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