Asterisk timer

Zaptel timers for Asterisk

There are at least two Asterisk applications that need support of a timer to work properly:

It may also be required with Music on Hold, i.e. to improve sound quality.

For Linux, several solutions exist to provide a timer, for other operating systems there is nothing, yet.

How to get a working timer

  • Zaptel hardware device will provide timing to Asterisk.
  • ztdummy is a dummy Zaptel device that provides no channels and only timing. It can use various sources for the timing
    • Linux kernels with HZ set to 1000. This was the default of kernel 2.6.0 - 2.6.12, and normally requires a kernel rebuild on newer kernels.
    • RTC support - works in i386 and amd64 as of 2.6.15.
    • HPET timers - for even newer kernels (right now requires an external patch, see ).
    • UHCI USB controller - abuses a timer in those USB controllers (controllers made by Intel or Via). Should work on any kernel.

The above should work with minimal tweaking in a default installation of Zaptel.

Some alternatives that have been suggested to ztdummy over the years:

  • If you don't have Digium hardware, there are three replacements:

Zaprtc works fine on SMP wth kernel 2.6.

Note: Zaprtc is actually a replacement for the standard RTC module. It provides the same facilities, but includes extra parts for Zaptel use. You will need to unload standard RTC module (rmmod rtc) or re-compile the kernel without RTC support (in your kernel source dir: "make menuconfig" --> Character Devices --> uncheck Enhanced Real Time Clock; now re-compile the kernel) in order to be able to use zaprtc.

For FreeBSD

For OpenWRT

Created by: oej, Last modification: Thu 06 of Sep, 2007 (19:14 UTC) by perepo
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