I’m going to lift a bit of preliminary text from a page on the FreePBX site entitled “How to give a particular extension different or restricted trunk access for outgoing calls“:

IMPORTANT: When implementing any sort of restrictions on extensions, using the method described here or any other method, please be absolutely certain that you do not inadvertently restrict access to emergency services numbers (such as 911 in the U.S./Canada)!

There is a recurring question that comes up every so often, regarding how to give one particular extension (or a group of extensions) access to a different trunk for specific outgoing calls, or perhaps to restrict access to a particular trunk. Usually this involves an extension that is accessible to people that might want to make calls that cost money, and you don’t want them to do that. But there are many other reasons to route calls differently for different extensions, while still keeping all extensions on the same system so they can call each other.

Usually when someone asks about this, a common suggestion is to use the unsupported third-party Custom Contexts module. While this module is very versatile and lets you have a high degree of control over what each extension may access, there are at least two downsides. One is that it’s not part of the official distribution and therefore, a future upgrade of FreePBX might “break” it.

(This is probably less likely now, because it appears some of the FreePBX developers have taken an interest in maintaining it, but it’s still not beyond the realm of possibility.)

The other issue is that you have to go through and check (and maybe change) all the priority dropdowns if you add, remove, or move a route, and that can get to be a pain in the butt very quickly if you are in the habit modifying your routes with any frequency.

The problem with this page is that although it discusses several alternatives to using Custom Contexts (and you may wish to read it just to learn about those other possibilities), it is getting rather dated and therefore does not mention the use of the fourth field in Outbound Routes, a.k.a the “CallerID” field, which is by far the easiest way to implement this.

Let’s say you have an existing outbound route, over which your outbound calls normally travel, and it has a particular selection of trunks.  But you also have an extension, let’s say it’s extension 234, and you want it to use a different trunk or group of trunks.  In FreePBX 2.9 or later, all you have to do is this:

• Go to the settings page for the Outbound Route that is currently used for outgoing calls.
• At the bottom of the page, next to the “Submit Changes” button, there is a new “Duplicate Route” button.  Click on “Duplicate Route”.
• Move the duplicated route to be higher in priority than the original route (it should appear just above the original route in the right-hand column).
• Optionally rename the duplicated route to something more to your liking.
• In the duplicated route, under “Dial Patterns that will use this Route“, add the extension number (or pattern matching a group of extensions) to the fourth (CallerID) field of EVERY dial pattern on the list.  Or, if using the Swiss Army Knife Module and you have checked the “Turn On Old (Pre 2.8) Dial Plan Textbox” checkbox (EDIT: or if you have FreePBX 12 or later, and under Settings | Advanced Settings, in the “GUI Behavior” section you have set Enable The Old Style FreePBX Dial Patterns Textarea to True), then add the extension number or pattern to the end of every existing pattern, separated by a forward slash.  As an example, an existing pattern of 1+NXXNXXXXXX would become 1+NXXNXXXXXX/234.  Again, you must do this to every pattern in the pattern list.
• And finally, in the duplicated route, change the the “Trunk Sequence for Matched Routes” to include only those trunks that you want that extension or group of extensions to use.

If there are additional Outbound Routes for which you want to change the trunk selection for the same extension, repeat the above, starting with the other outbound route(s).  If you have additional extensions and you want one or more of them to have different trunk usage, repeat the above, using the different extension number(s) in the CallerID field and the different trunk selections.

If you want to block an extension’s ability to make toll calls, use the same procedure but only give them access to an ENUM trunk.  ENUM is pretty broken then days, it it would be rare for a call to actually complete, but if it does it’s not going to cost you anything.  This particular usage is discussed in more detail in “How to block a single extension’s ability to make outgoing toll calls in FreePBX“. (EDIT: In the most recent versions of FreePBX you can simply not select any trunks at all in the “Trunk Sequence for Matched Routes” section of the Outbound Route, and then optionally select a failure announcement or whatever treatment you want to give the call in the “Optional Destination on Congestion” section.)

And again, please note that you can use a single extension number OR a pattern in the CallerID field.  For example, if you had a pattern like 1NXXNXXXXXX, you could do something like:

• 1NXXNXXXXXX/100 – match on the pattern only if the call is from extension 100
• 1NXXNXXXXXX/2[45]X – match on the pattern only if the call is from an extension in the range 240-259
• 1NXXNXXXXXX/3XX – match on the pattern only if the call is from an extension in the range 300-399

And if you wanted to allow the call only if it came from extension 100, 240-259, or an extension in the 300’s then you could use all three of the above rules in the same outbound route.

I will offer my opinion that using the Swiss Army Knife Module and checking “Turn On Old (Pre 2.8) Dial Plan Textbox” is the only way to go if you happen to have several hundred dial patterns!  Well, maybe not the only way (you could export a .CSV file, edit it, and import it back in), but definitely the easiest, because you can simply cut all the patterns from the textbox and paste them into a text editor, then use search-and-replace to add the extension numbers, then copy the changed patterns from the text editor and paste them back into the textbox in the Outbound Route.  If the search-and-replace function supports regex matching then it’s easy – set the find string to n and set the replace string to /234n (assuming 234 is the extension number you want to add), and replace all occurrences (be sure to check the first and last lines to make sure they look as they should, in case there was a missing or extra newline character somewhere).

EDIT: We have been informed that the old-style textboxes are once again available in FreePBX 12 and later. You have to click on the Settings tab, then Advanced Settings, then find the “GUI Behavior” section and change the Enable The Old Style FreePBX Dial Patterns Textarea setting to True.

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