Paging Fails After ~130 Extensions

We are currently running Trixbox CE v2.6.2.3 using Asterisk 1.4.22-4 on a Dell Poweredge SC1435. The phones we use are a mix of Polycom Soundpoint IP 320's and 650's, for a total of 188 internal extensions.

To give a quick history, we have multiple paging groups setup, the majority consisting of specific departments which contained no more than 60 extensions for each group. The one exception to this was a single paging group which consisted of all internal extensions for emergency purposes. At the time that this massive group was setup all of the internal extensions were confirmed as being paged.

Now, 2 months later, what happens is that when this paging group is used, the Trixbox will attempt to add all of the extensions to a conference as normal, but will fail to add additional extensions after about 130 to 140 extensions have succeeded. This number at which it begins to fail varies each time we test this paging group. The error message received is "WARNING[XXXX] app_page.c: Incomplete destination '' supplied.". The first 130-140 extensions will join the conference and hear the page as intended while the rest will hear nothing.

At the time of first setup the Trixbox was completely configured, the only changes to it since then have been the addition and removal of extensions as employees have been hired or leave us. As the default paging group, the paging group in question has been updated with these changes as well.

The settings on the paging group are as follows:

1. Consists of 188 extensions.
2. Force if busy: On
3. Duplex Paging: Off
4. Default Page Group: On

A log of the initial page can be found at http://pastebin.com/m61703a31

Does anyone know if there is there a limit to how many extensions you can have in a paging group? If so, is there an alternative other than paging each department one at a time?

Otherwise, does anyone have any ideas what might be causing it?

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Summary:

1. Paging Group consisting of 188 extensions
2. Worked 2 months prior, no changes were made to the group itself other than adding and removing extensions
3. Only 130-140 extensions successfully paged
4. The rest hear nothing after the error: "Incomplete destination '' supplied."