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T1-CAS and Ghost Calls

a.gooding
Level 5
Level 5

Hi,

we just implemented a CCME 4.2 (c3825-ipvoicek9-mz.124-11.XW3) solution that for the most part works great. i have however, encountered an issue that ive not seen before. we have a T1-CAS configured and did a connection plar to a hunt group.

now calls in and our are fine however, when phones are idle, they receive rings from the PSTN but its not actually a call. more of a ghost call. this is happening every half hour or so but not too sure where to start.

attached are the debug voice ccapi inout logs i asked the customer to collect. im not a guru in reading the debugs, but it seems to me that the router thinks its an actual call, thus leading me to beleive the issue is signaling. below are the times and extensions that are ringing with the ghost calls. any assistance with this would be greatly appreciated.

7:04pm 22018, 22019

7:24pm 22018, 22019

7:28pm 22018, 22019

7:31pm 22018, 22019

7:38pm 22018, 22019

7:41pm 22018, 22019

7:43pm 22018, 22019

7:45pm 22018, 22019

28 Replies 28

paolo bevilacqua
Hall of Fame
Hall of Fame

Hi, these traces don't do much to help finding the problem. Check with "debug vpm signal" if there is some trunk activity at the time of the ghost call, and if there is send it here.

got it, will collect that debug and send asap

Got through,

went down to the customer site to see what was going on. I configured the T1 for the full 24 channels, but carrier only had the first 12 channels. channels 13-24 were in a siezed state and this caused the phones to continously ring. reconfigured timeslots to only 12 channels and working fine.

thanks again

Hello,

I'm about to do a T1-CAS to CCME install, and had a few questions. The service the provider is giving us what they call a T1-DEA service from what I found this is the same as T1-CAS but it seems as though there are a few types of configurations for T1-CAS. Can you recommend one that gives us the most functionality (ex: caller ID)?

Thanks Ryan

Hi Ryan, the answer is T1 PRI. All varieties of T1 CAS do miss important features.

Yeah PRI is not an option, it's a remote area and the services is not provided there. So T1 CAS is all I got

Ask them in which way they can provide CLID then.

Wow, you must have had better experiences with service providers than I had in the past. My experiences have really been trial and error, and asking the service provider for help is like talking to a wall. The reason I'm posting for advice on Net Pro's is to give me something to work with when I do have to bring this circuit up next week.

So has anyone had any experiences with T1-CAS.

What can I expect?

Thanks Ryan

Usually, there is no CLID/ANI on T1 CAS, sometime they provide it in the DNIS via * delimited format. Or they could provide it in-band as true CLID for FXO connections.

Not all SPs are like you say. Now if the one you're dealing with is so bad, good luck bringing up the circuit in first place, hopefully during the bring-up phase you will locate an competent individual to talk to.

These individuals are usually well shielded from the general public until when absolutely necessary.

The good news is that the router can support anything they can possibly come up with.

Pb Is right, cas usually does not support caller ID. I am in fact in the process with Verizon of changing or cas t's over to pri's to support clid.

Caller ID in both directions I assume. So what does the users see? "Unknown"? And when you say CAS "usually" doesn't support caller ID, does this mean if you can not get Wink-Start feature group d?

So the only other alternative to this service is analog. But the density of lines required is too large. So I guess T1 CAS is the best we can do.

Caller-id properly named, is the inband modulation that you have on analog lines. In theory nothing prevents it to be T1 CAS FXO.

In digital telephony, CLID is replaced by ANI, and the called number that you need for DID, is called DNIS. In T1 CAS, these are sent as MF digits with a delimiter like a star. I had to develop a script for that because IOS support for this format was supposed to exist but is broken.

These are ALL sent network to user. User to network, you have full bidirectional with PRI only.

Hope this clarifies.

I think follow. I found a reference to a bug where the IOS written for the ISR's do not allow for ANI/DNIS info to be passed in Delimeted format example ani/dnis would look like 5556661234*4447771234.

So did you write a TCL script to make this work?

Ryan

Hi Arvind,

We see a lot of customers, when forced to use CAS instead of PRI, will use a mix of wink/immediate start and FGD trunks.

Check out this doc:

http://www.cisco.com/en/US/docs/ios/12_3/vvf_c/cisco_ios_isdn_voice_configuration_guide/isdn09.html

FGD will allow you to receive the inbound caller ID.

Thus, it's common to see a trunk of half FGD half wink start. They use wink start for outgoing calls, and FGD for incoming calls for caller ID.

As far as the different signaling methods go, wink-start is far more common than anything else.

hth,

nick

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