Interdigit Timeout with Legacy PBX via PRI

[jaimeatnok]

As mentioned in a previous conversation, we've got a Cisco 2821 ISR running CME 4.0(2) which is connected to an Alcatel 4200 legacy PBX. The ISR is a gateway to the PSTN so the Legacy PBX sits behind it, connected via an E1 link (Primary Rate Interface).

In order for the Legacy PBX to reach the PSTN, it adds a prefix ("5432") to each call placed. The ISR then uses this prefix to match an outgoing dial-peer. This configuration has been tested and works fine.

The only snag is that there's a HUGE delay between the last digit being received from the Legacy PBX and the ISR actually placing the call.

On the Serial interface to the legacy PBX we need to run "isdn overlap-received" because the Legacy PBX sends the digits one by one. I've got the "interdigit timeout" on all concerned voice-ports set to 3 seconds. I've also tried playing around with several ISDN timers but no results.

I've tried changing the timeout values but I still get roughly a 15 second delay between the last digit being received and the actual call being placed.

[jaimeatnok]

Hi,

I haven't got any network-clock commands, should I configure these for the E1 port connected to the PSTN and the Legacy PBX? I do know that for data E1, one end must be clock-master and the other end clock-slave.

The output of "sh controllers e1" is:

E1 0/2/1 is up.

Applique type is Channelized E1 - balanced

Description: PSTN

No alarms detected.

alarm-trigger is not set

Version info Firmware: 20060711, FPGA: 13, spm_count = 0

Framing is CRC4, Line Code is HDB3, Clock Source is Line.

CRC Threshold is 320. Reported from firmware is 320.

Data in current interval (318 seconds elapsed):

0 Line Code Violations, 0 Path Code Violations

10 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins

10 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

Total Data (last 9 15 minute intervals):

0 Line Code Violations, 0 Path Code Violations,

244 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins,

244 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

E1 0/3/0 is up.

Applique type is Channelized E1 - balanced

Description: PRI_ALCATEL_4200

No alarms detected.

alarm-trigger is not set

Version info Firmware: 20060711, FPGA: 13, spm_count = 0

Framing is CRC4, Line Code is HDB3, Clock Source is Line.

CRC Threshold is 320. Reported from firmware is 320.

Data in current interval (318 seconds elapsed):

0 Line Code Violations, 0 Path Code Violations

10 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins

10 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

Total Data (last 9 15 minute intervals):

0 Line Code Violations, 0 Path Code Violations,

272 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins,

272 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

[paolo bevilacqua]

Hi,

please configure

network-clock-participate wic 2

network-clock-participate wic 3

network-clock-select 1 e1 0/2/1

this should eliminate the slips.

But I think you also need to provide clock to PBX, so configure clock source internal under controller E1 0/3/0.

[jaimeatnok]

Hi,

This seems to have cleared up the problem, thanks!

RE the IOS upgrade, I'm waiting for Cisco to register the SmartNET package as there seems to be a problem with registering the end user's address so the whole process is being taken care of by Cisco's helpdesk.

I'll let you know after I've upgraded the IOS.

[paolo bevilacqua]

Glad to know it helped.

you need to insist with cisco to get the registration done, sometime their system doesn't work and you have to call many times.

[jaimeatnok]

Finally the SmartNET has been registered and I'm furiously searching the Cisco IOS Software Download to make heads or tails out of the never ending list of IOS versions!

At the moment we've got:

- CME 4.0.2(3)

- IOS 12.4(13r)T

We want to upgrade to:

- CME 4.2

- A higher IOS revision but as far as I can see, CME 4.2 is supported only in 12.4(11)XW2 or XW3

It seems that by upgrading to CME 4.2, I'll have to go down an IOS revision....can this be right?

[paolo bevilacqua]

You would actually loose only the features that are in 12.4(13)T but not in 12.4(11)T. For telephony, that means none.

If you really want CME 4.2, your only choice is 12.4(11)XW4.

[jaimeatnok]

Yes, I thought so...for the 2821 its actually XW3 as XW4 seems to be for the UC520 and an 17xx series routers.

Where could I find some sort of changelog of telephony features for IOS versions? Navigating the IOS upgrade portal is sometimes frustrating as the information is very patchy.

[paolo bevilacqua]

You are right, XW4 has been released for the 1861 only for now.

The changelog you want is the IOS release notes. It lists the new features as bugs fixed.

[jaimeatnok]

Hi,

Yesterday I upgraded the software on the ISR 2821 to the following:

- IOS 12.4(11)T2 to 12.4(15)T1

- CME 4.0.3 to 4.1(0)

However, calls from the Legacy PBX to IP phones are still received without a Caller ID...