Problems with interdigit timeout

[ev1205]

Hi everyone !!!

We have  new CUCM ver  10.5.1.10000-7 platform, on a HA schema with one Publisher and one Subscriber

To implement a intecompany connection to an external PBX, with configured the Route Pattern 3XXXX pointing to our voice gateway.

But our customer has internal directory numbers 3XXX.

Well when we call to intercompany 3XXXX numbers we don't have problems, but when we dial internal DN 3XXX the time to generate the call is too long.

I understand that out default interdigit time out ( 15sec) is causing this situation, As I understand I must change T302 timer to something lower that 15000 msec, I would like to confirm:

a) I have to restart CUCM Cisco Call Manager sevices on both servers ( Pub and Sub)??? Or only on Publisher.??

b) Is there another solution avoiding this T302 modification and services restarting ??

THANKS to everyone for your help

Enrique Villasana

[Jaime Valencia]

That was some very poor decision making right there, the only real way to fix this, is to either change your dial plan, or the route pattern, anything else, would just be a patch, and you would still get delay, even the T302 has a minimum setting you can't go beyond.

[Wilson Samuel]

I agree with Jamie on this one. Going forward with an overlapping dial plan is never a good idea, it will create too much confusion and dissatisfaction for the end users.

The changing of T.302 will make it almost impossible for certain users to dial e.g. 3001 and 30010.

Just wondering why go ahead with 3XXXX and 3XXX dial plans?

Is the PBX also part of your same company?

HTH

[Jitender Bhandari]

Hi

Overlapping dialplan is the worse thing we can do to CUCM, i can understand due to some real like scenarios there are time when it is unavoidable.

We can try implementing the fix in couple of way.

1. Try separating the two partitions between different CSS if possible and be choose the way you apply your CSS.
2. Check Urgent Priority on 3XXXXX.

As you are the best judge to your dial plan, i would like to explain how Urgent Priority works

Urgent Priority

•The Urgent Priority checkbox is often used to force immediate routing of certain calls as soon as a match is detected, without waiting for the T302 timer to expire. For example, in North America, if the patterns 9.911 and 9.[2-9]XXXXXX are configured and a user dials 9911, Unified CM has to wait for the T302 timer before routing the call because further digits may cause the 9.[2-9]XXXXXX to match. If Urgent Priority is enabled for the 9.911 route pattern, Unified CM makes its routing decision as soon as the user has finished dialing 9911, without waiting for the T302 timer.

•It is important to note that the Urgent Priority checkbox forces the T302 timer to expire as soon as the configured pattern is the best match for the dialed number. This does not mean that the urgent pattern has a higher priority than other patterns; the closest-match logic described in the section on Call Routing in Unified CM, still applies.

For example, assume the route pattern 1XX is configured as urgent and the pattern 12! is configured as a regular route pattern. If a user dials 123, Unified CM will not make its routing decision as soon as it receives the third digit because even though 1XX is an urgent pattern, it is not the best match (10 total patterns matched by 12! versus 100 patterns matched by 1XX). Unified CM will have to wait for inter-digit timeout before routing the call because the pattern 12! allows for more digits to be input by the user.

Consider another example, where pattern 12[2-5] is marked as urgent and 12! is configured as a regular pattern. If the user dials 123, the pattern 12[2-5] is the best match (4 total patterns matched by 12[2-5] versus 10 patterns matched by 12!). Because the T302 timer is aborted and because the urgent-priority pattern is the best match, no further user input is expected. Unified CM routes the call using pattern 12[2-5].

reference

http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/9x/uc9x/dialplan.html#wp1043756

So if 3XXXXX is best match it will send the call right away an brake the T302 timer value.

Another way around.

Variable Length On-Net Dial Plan

Systems with many sites or overlapping site extension ranges can benefit from the use of a variable-length dial plan with the following characteristics:

•Within a site, the system retains the use of abbreviated dialing for calls to on-net extensions (for example, four-digit dialing).

•Between sites, users dial an access code followed by a site code and the destination's on-net extension.

•Off-net calls require an access code followed by a PSTN number.

The use of access and site codes (see Table 9-3) enables the on-net dial plan to differentiate between extensions that would overlap if a uniform abbreviated dial plan were implemented.

Table 9-3 Typical Use of Site Codes 

Site Code	Range	Use	DID Ranges	Non-DID Ranges
1	1XXX	Site A extensions	418 555 10XX	1[1-9]XX
2	1XXX	Site B extensions	919 555 1XXX	N/A
3	1XXX	Site C extensions	907 555 1XXX	N/A

In Table 9-3, sites A, B, and C are independently assigned the four-digit range 1XXX. For calls from site A to site B under the old telephony system, the calls had to be routed as off-net calls. With the new system, these calls can be dialed as on-net calls.

From site A, users simply dial 1234 to reach extension 1234. But from site B, the dial plan must accommodate the ability to reach extension 1234 at site A without conflicting with site B's own extension 1234. Therefore, each site is assigned a site code.

From site B, merely dialing the combination of site A's code with the desired extension is not feasible: in this case because 11234 would partially overlap with site B's extension 1123, thus causing interdigit timeout issues. If, instead, we assign 8 as an inter-site on-net access code, this would allow site B to dial 81234 to reach site A's extension 1234.

The following factors determine the quantity of digits required to dial an on-net, off-site extension:

•One digit for the inter-site access code

•N digits for the site code, where N is chosen to satisfy the quantity of site codes required (For example, if a system has 13 sites, then a minimum of two digits are required for the site code.)

•The quantity of digits required by the destination site's local dial plan

For example, a system with 75 sites which each use four-digit abbreviated dialing would require a format of 8 + SS + XXXX, where 8 is the on-net access code, SS is a two-digit site code, and XXXX is a four-digit extension number, giving a total of seven digits.

HTH

JB

[arthurblackmouth · Accepted solution]

Hi

I recommend you creating a prefix for some of the cases, for example:

You have this two scenarios:

3XXX, and 3XXXX

So, if you want to call to some extension for the group 3XXX, creates a prefix to dial 1752.3XXX, then, you'll have to create a router pattern like this 1752.3XXX to send only the last 4 digits to the RL

This kind of methods are very common when you have more remote offices with the same dialplan.

Only consideres warn users as dialing 

I hope will be helpful.

Regards

Arthur