Changing Trunk Selection Prefix – On NEC NEAX 2000 IPS

Sometimes it’s necessary to add or change your numbering plan, so as to enable or disable users of the NEC 2000 IPS phone system to select a specific trunk when dialling a number. The most common use for this (in the UK, at least!) is using 9 to select the first preferred trunk to the PSTN. This will most likely be a trunk, such as an analogue circuit, ISDN2 or ISDN30 circuit or a SIP trunk.

Taking a step back for a moment it’s worth mentioning that in this subject arena, you have Trunks, Trunk Groups and LCR Plans.

A trunk is usually single line (or channel) – but when you have hardware like ISDN2 or ISDN30 circuits, you have to bundle lots of trunks together in one big configuration, so when you need to use it, you select anything that is available on it! This forms a Trunk Group.

Once you have built a Trunk Group you usually access them via an LCR plan – this enables you to bundle lots of trunk groups together in one big plan and decide on restrictions and specifics of how it’s used – like what numbers should be restricted, how many numbers to wait for before sending the string the trunk itself.

So, lets hop into MOC mode and take a look. You can find a quick guide on using MOC mode here, but I will try to explain all the key presses as we go….

Go into MATworX and select MOC from the menu.

Now remember, that you start a command with a forward-slash (/), you submit each item of data using the <spacebar> and you only execute a command when using the full stop (.)

We want to look into the number plan, so press / and you’ll see “COMMAND>” return on the screen. Then type 200 (CM200 is Number Plan Zero) followed by the number the user would dial for the trunk you’re interested in. To see an overall view, you could start with zero (followed by space bar) and use the enter key to scroll through all 10 of the numeric 1-digit number plan entries to see what data is already in your system.

Your screen will look something like this.

The image shows the number plan numbers from 0 to 9 and, keeping this brief the replies are as follows:

0: 801 = 0 goes to a 1 digit internal destination

1: 804 = 1 goes to a 4 digit internal destination

2: 804 = 2 goes to a 4 digit internal destination

7: A129 = 7 goes to LCR plan A129

9: A129 = 9 goes to LCR plan A129

The bits we’re interested in for Trunk selection is anything that has a second data of 1xx (a specific trunk) or anything that has a second data of Axxx (an LCR group which could contain the specific trunks).

Now, in the UK, 99% of systems ever built in the UK would have A129 pointing to any available ISDN or Analogue PSTN trunk. Thats how it is – I can go into further detail about how to determine what is inside an LCR plan, but that’s another story – just trust me on this one!

So you can be pretty sure that if a number in your number plan goes to A129, that’s going to hit any PSTN trunks you have. If you want to MAKE a number in the number plan access that LCR plan, then simply do the following:

CM200 > 8 : A129

thats

Press Forward Slash to get “COMMAND>”, followed by 8 and the <spacebar>, then type A129 and press “.” (full stop)

If you want to DELETE a number in the number plan which accesses that LCR plan, then simply do the following:

CM200 > 7 : A129: CCC

thats

Press Forward Slash to get “COMMAND>”, followed by 8 and the <spacebar>, then type CCC and press “.” (full stop)

In this instance, you’ve made 8 select LCR group A129 and removed 7 from selecting LCR group A129.

Any questions, feel free to ask in the comments box below!