Cisco FXO with Asterisk still getting a lot of play

I keep an eye on my logs and for as long as I can remember this post has been the most popular:

It’s funny that almost 3 years later very little has changed.  I’m running Trixbox CE now but the configuration is still pretty much the same.  I’m pretty happy with how TB has progressed and I’ve stuck with it.  For a while I was running it virtually and while that worked ok it always had problems with the clock slipping.  I’m now running on an older P4 and all’s well.

Regarding my old config, a couple of things seem to come up with the folks that find that post.  First, you don’t want the OPX version of PLAR.  I’m not really sure why Asterisk isn’t happy with it but it has to do with the order of going off-hook.  Just use the regular PLAR and you’ll be fine.  Also, make sure you put the trunk into the proper context on Asterisk.  I say “proper” because everyone will be different.

If someone has a good resource for understanding the proper way to configure contexts, please let me know.  I understand the basic nature of it, after all it’s similar to Partitions and Calling Search Spaces on CallManager.  But it doesn’t seem clear to me that there’s a simple way to manage them.

3 thoughts on “Cisco FXO with Asterisk still getting a lot of play

  1. In my case, I’m using straight-up Asterisk under Ubuntu.  Up until recently, I was using a PCI modem card as an FXO device and a Sipura SPA-1001 as an FXS device.

    However, owing to the fact that my modem cards are PCI devices, I had little choice but to keep Asterisk on the bare metal, precluding the use of ESX Server 3i–a freebie, which is what I wanted to use.  So my other infrastructure machines handling mail and DNS had to be virtualized with VMware Server.  I didn’t want to mess with Xen because FreeBSD doesn’t install paravirtualized very well on older hardware without VT-x/AMD-V instructions.

    With this Cisco handling my FXO and FXS ports, I can now consider ESX 3i as an option.  Though of course, the time and timing might be an issue, so I have a separate computer running ESX 3i I can actually prototype on.

    Though for your part, what were you using to handle virtualization?  I’m running a am older Northwood-class P4 Del OptiPlex GX270 I picked up from the county surplus yard for a song.  Right now, I’m using VMware Server 2.0.0 on that machine which seems to be handling my auxiliary tasks pretty well.  That and VLAN support set up in the host and bridging set up along with a Cisco switch I picked up at the same place allows me to use my eight bridged statics without having to insert any cards (which I don’t have the room for anyway because both slots are full) or use any more switchports than is needed.

    I’ll have to work up on my study of contexts; I think I understand them as well, and I’m making more sense of them as I work my extensions.conf file (I’m not using trixbox; I’m hand-editing the extensions.conf file).  Running the Asterisk monitor at a shell prompt also helps a lot when debugging configs.

    Anyway, that’s all for now.  Am going to have fun with virtualizing things and seeing if I can keep them working as they should.


  2. Most of the time my virtualization consisted of what you’re talking about there.  Older P4’s with as much ram as I can find running VMWare Server 2.0.  I also tried ESX 3i on a couple different machines and had numerous problems getting it to install.  It seems to prefer newer hardware.  I was even running the pre-built TB VMWare image and still having clock sync problems.

  3. Actually, I had no trouble installing ESX 3i on the hardware I described (in fact, I have a rig running right now ready to receive VMs).  I did have to edit one script per instructions I found on a site; other than that, it installed with minimal effort.

    A great resource for playing with ESX 3i is  It had those instructions for installing ESX 3i on stuff that was a bit outside what it really wants.  About all that it had any real “trouble” with was the IDE controller.  It worked, so I’m happy.

    Hope this helps out.


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