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New Member

H.323 with RG/RL gets busy tone so stops routing

Little bit of an issue which you might be able to help me with please.

The “customer” has a requirement for E&M links to a legacy PABX system, which we have installed 2 x 1760 with 8 E&M in each.

Each unit has a RG and then 1 RL pattern 505…. Pointing at the 2 RG’s.

First unit is fine and all is dandy. Problem is when all 8 ports are busy the user dialling the 505 get a “busy” tone, which is what I think the h323 gateway is sending back.

This is normally fixable by setting the Continue routing on busy flag in service parameters, however we can not use this feature for a different reason (that being if the CCM can not find the telephone number locally in DB then lower Partition with route XXXX to the legacy system. This is fine, however there will be a serious looping issue if the user has migrated and is on the IP phone as it will go to legacy and then the legacy will say “no there is a cfwd to CCM!”)

Now I guess I could fix with Location Control (setting bandwidth max to 8x80=640kb) however this will cause an issue if one of the ports is busied out, which happens quite a lot. I think the same could be achievable using a GK however I don’t really have one, although I suspect only the same benefit as Location CAC.

I thought about a 9th dial peer (voip) on the first gateway (preference 9) pointing at the 2nd gateway but that doesn’t work.

Is there any chance of changing the “busy” behaviour (h225/h245)? The user is not busy, it is the gateway which is a different thing.

Have seen lots of talk on Netpro about this. The real answer must be change the gateway behaviour to send back error rather than busy if the lines are unavailable, only send busy if the USER is busy.

Ideas (and a solution) gratefully received!

Cisco Employee

Re: H.323 with RG/RL gets busy tone so stops routing

I do not have an answer for your question, but wanted to give some thoughts.

Your 9th dial peer will not work because preference kicks in only if the dial-peer type etc.. are the same

I wonder if you can have one set of phones point to the first gateway and another set of phones point to the second.. When you do this, you can also add locations to use the second gateway, you achieve a fairly balanced call load. Not the best scenario I agree..When a port is busied out, you might see some issues, but not all calls will fail.

One other thing to keep in mind is that TCP might timeout when it is hunting all the dial peers/ gateways.

You do not have an option to manupulate CCAPI cause codes, unlike ISDN cause codes. So, that will not work.

New Member

Re: H.323 with RG/RL gets busy tone so stops routing


Thanks for the reply, however as mentioned you cant use locations as periodacally some of the circuits get busied out for maintenance (or wire disconnect) and when this happens the location control b/w machanism wont work (as it never gets to the CAC limit to fail over to the 2nd gateway)(although you could accept this as a risk i guess).

I have been able to go back to enabling the route on busy as incase people missed this point, that option is only for H.225 and H.323. It might be obvious but you never know when these Bboards are usual. MGCP is not affected by this service parameter!. Also there is an outstanding bug in the help page for the service parameter "route on busy" as it talks only about cluster links, but it is confirmed that it actually means any H.225 driven communication.

Re: H.323 with RG/RL gets busy tone so stops routing

You could try changing this distribution algorithm on the route list/route group configuration to circular. This distribution algorithm will send equal amounts of calls to each gateway.

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