General Rule for CSS !

[Jonn cos]

Hi all.

I have read (and practiced) that partitions are assigned to any entity that is DIALED. That is the general rule of thumb. But i have seen CSS being assigned to lots of different things, so whats the general rule of thumb for CSS ? to which ENTITY does the CSS assigns to ?

Kindly guide

[Aaron Harrison]

Hi John

You are learning a lot this week :-)

Basically, it's like this:

- On a default system, with no partitions and no CSS configurated - everything is diallable, by everything else. No restrictions.

- If you then assign everything to new partititons - nothing is diallable. Even if two DNs are in the SAME partition, they cannot be dialled

- To make them diallable, a DN must have a CSS containing the partitions it is to be allowed to dial.

For example, if a DN(1234) and a route pattern (9.@) are in partition A, then DN(4321) must have a CSS containing partition A to be able to dial DN(1234) and route pattern (9.@).

DN(1234) would need a CSS containing Partition A to be able to dial (9.@).

Everything that can originate a call should have a CSS (so gateways, trunks, translation patterns, DNs, etc etc).

Everything that can be called should be in a partition (which would also include DNs, translation patterns, but trunks/gateways would not have a partition - these are reached via route patterns, so it's the route patterns that have a partition).

Regards

Aaron

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[Jonn cos]

Thanks Aaron :-)

Sir your statement is the actual confusion of mine

Everything that can originate a call should have a CSS (so gateways, trunks, translation patterns, DNs, etc etc

My understanding is, Phones can dial a number, how come translation-pattern and DNs can originate a call ??

[Saurabh Agnihotri]

The lines and Translation Patterns have CSSs to give you more granularity.

If you only have a CSS on the phone and not on lines, then you will not be able to dial a number from any line on the phone.

Whereas, if you have  two lines configured on the phone, you may be able to make calls to certain destinations from one line and not from the other (based on how the partitions and CSSs are configured).

Regards,

Saurabh

[Aaron Harrison]

Hi John

Well -

A translation pattern has two 'sides' - an 'inwards' side if you like, where it has a pattern (e.g. 1xxx to match anything 4 digits starting with 1). This pattern goes in the dial plan, and since it is diallabled, it needs a partition.

When you dail the translation pattern, it gets translated to another number - in the example above, it may be translated to 3xxx. To reach 3xxx, the translation pattern needs a CSS. So a translation has a partition to make it diallable, and a CSS to determine what it can 'dial'.

A phone cannot make calls at all - UNTIL it has a DN (Directory Number, or 'line') assigned to it. When you configure a phone, you cannot configure a partition on the 'phone', you must add a DN, and configure a partition on the DN.

When it comes to dialling, there are two CSS involved. You can assign a CSS to the phone, and a CSS to the DN. In some designs either will work the same (i.e. with only routing CSSs), but in some designs it is customary for the phone to have a CSS that routes any call in an unrestricted fashion, and a DN (or line) CSS that blocks calls that should not be permitted.

Regards

Aaron

[Jonn cos]

Sir its a bit confusing,

If translation-pattern specifies 1001 to be translated to 3001, its just doing the translation and leaving the rest to cucm dial plan logic, why it needs a CSS. Translation-pattern is not actually DIALING 3001 right ? or am i wrong ?

[Jonn cos]

Or can i summarize what you said above to

"Any thing that needs to reach a dialable pattern, must use CSS to do so !"

Is above statement correct ?

[Aaron Harrison · Accepted solution]

Yes, that pretty much summarises it. The only exception to that is stuff in the partition, which is always reachable by anything. It's considered bad practice to use partition in pretty much all cases.

Re: translation patterns, it has a CSS (rather than just inheriting the CSS used with the original call) to add flexibility. You can use the CSS on the translation pattern to change where the call would go to - for example, you could translate 1001 to 1001, but when it hits the trans pattern it then uses the translation patterns CSS, and the call could go to a different 1001 than it would have reached if the translation pattern did not exist or had a different CSS.

Why would you have different 1001s? Well...  you might in a multi-tenant scenario for example. TWo DNs could both be on the system, and if they are in different partitions they are completely different numbers. One could be a normal phone/DN, and the other might be a UCCX pilot number.

Another example might be if you were DN(1234) in parition A, and you had a DN(2222) in partition B. Say that DN(1234) only has partition A in it's CSS. Now it cannot dial 2222.

If you added a trans pattern for 2222 in partition A, set the tranlation mask to 2222 and set the CSS on the trans pattern to be one that contained partition B, then DN(1234) can now dial 2222.

Any clearer?

[Jonn cos]

Thanks alot for the explanation Aaron.