Asterisk on VMWare

Hey members

I am new to Asterisk and virtualization with VMWare, although I have experimented with Hyper V on Server 2008. However I have now become interested in implementing Asterisk, FreeNAS, and monowall onto one machine for home use. While I was searching on VMWare appliance marketplace I found a few different preconfigured VM’s and I was wondering which ones forum members have used with success.
I am also wondering if VMware would allow me to use a Digum FX0 card like this one avaliable on ebay. Right now I have 2 PTSN lines and all standard analog phones but I will be buying some IP phones soon. I wanted to use the IP phones with these standard lines for now and I will think about getting a ‘full’ VoIP setup with some digital trunk lines. I just wanted ot make sure of the compatibility. Also if anyone has any trick or hints for setting up VMWare then just post it on the thread.

Also: Should I use VMWare ESXi or VMWare server? I think that ESXi is the better option since it is newer, but I don’t know much about virtualization.

Thanks for all your help


VMware (and I am pretty sure HyperV) dont allow the use of any specialized hardware so running a TDM card on the server is not really an option.

Secondly Asterisk runs like crap on VMware. Do a search on these forums and you’ll see dozens of posts complaining about voice quality on VMware. Get an old crap desktop that has 256MB ram and run asterisk on CentOS4, it will run great for two or three simultanoues calls.

Third, ESXi is not better just because its new, its better because the way it works. ESXi (and its big brother ESX) are bare metal installs built from the ground up with nothing else in mind but to run VM’s on top of it. VMware Server (v2 is in beta now) runs on top of any host OS (windows, linux etc) and therefore depends on the host oerating system which was not designed from the ground up for running VM’s. HyperV is a cross between the two. HyperV is a “bare metal” system like ESX but its still just windows 2008 code that has been optimized for running VM’s.

I understand the difference between ESXi and VMWare server (basically ESXi is an operating system that is designed only to run other OS’s virtualized). However is the call quality through asterisk on VMWare unusable or is it not up to par with standard phone service (unvirtualized, standalone). I would rather not run an extra PC 24/7 for what is basically an experiment not because I don’t have the hardware (I have several P3 desktops) but because of electricity consumption.

If VMWare is not an option at all, then is there any other method to run all of these OS’s on one single PC? (including the FXO/TDM card) I am building a new server for these few applications so hardware requirements can be disregarded.

I have not personally tried Asterisk on ESX yet. I did on VMware server and I considered it unusable. Technically ESX (or ESXi) should do a much better job but again I have not tried it. There is NO way to get VMware to see the TDM card so using the card is not an option anyway.

If all your apps arelight load you “can” put them all on one box with the same OS. There is no requirement that Asterisk run by itself. If you do that make sure you dont install (or at least run) any type of X based GUI as that will for sure kill Asterisk.

The issue with VMware and with running other apps with asterisk is timing. Computers can deal with millisecond delays, but a human ear is very aware of delays and missed sounds and they will complain about it. Does this sound familiar to you “can you hear me now, Hello, Hello, HELLO!!!”? When Asterisk processes the audio it needs access to the processor and memory the exact microsecond it needs it not as soon as possible. VMware adds a layer in between and therefore adds time to the trasaction, which is why ESX should in theory be better as its designed to add as little overhead as possible. The same thing happens when you have other services on the same server eating up CPU resources, Asterisk may have to wait for those other processes to finish.

If this is all for testing or VERY small implementations the go for it, you have nothing to loose except your time.

Okay I now understand this better - if I remember correctly, VMWare stuff has to change the instruction set of the guest OS to the x86 instruction set, and this adds delays.

That is too bad then - I was hoping I could run it on one PC, but if there is no reasonable way to do it, then I will have to run a standalone for my tests, and if I really find it useful, then I will think about some of those embedded PC’s and run it on that.

thanks for your help swaterhouse

I have run Asterisk on VMware ESX 3.5 and there are timing problems due to the nature of virtual machines and the timing provided to the guest operting systems.

The main problem that I found was not actually with the quality of voice call, it was more with the quality of recorded annoucements (inc. IVR) and with voicemail. There was significant breakup on some of these announcements. We did some tweaks on VMware that hade it much better (there are some recommendations on the VMware Knowledge base for realtime applications) but the problems never went away completely.

And as has been mentioned by others VMware does not allow the use a specialist hardware link TDM cards.

I agree on the recent post on this thread. I am running asterisk on ESX for almost half a year now. However, we still have some issues on the timing and voice quality. When you checked the CPU resources, memory consumed by asterisk only on the esx, you can’t find any problem on it but in reality because there are other VM’s running in ESX at the same time, it will affect it. If your goal is for a very good voice quality, you should not use virtualization on asterisk. If you just want to test on it, or use it only for very few calls, you can use virtualization. Hence, IVR’s inside your asterisk will sound like choppy. I hope that someday, they can fix the issue on virtualization.

hi i run run Asterisk on VMware ESX 3.5 and everithing was okey my virtual machine run whith any problem
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