Newbie Question system requirements

Hi, everyone,

I’ve been tasked with setting up a PBX for a private network. It’s a mesh network with absolutely no outbound calling capabilities at this time (although we might add that in the future). The total number of extensions is expected to be 30 (if it increases, we’ll redesign our system appropriately). Our PBX system is going to be hosted on VMWare ESXi running on an IBM x3550 server (again, at least for now). The system is going to be the most basic that I can setup probably without voicemail capabilities even.

My biggest question is how much hard drive space do I need to set aside for this system? My second question is how many NICs do I need to allocate for the system (I have two physical ones enabled on the server, but can enable four total)? I should add that short-term, we’ll only have about five to ten phones total. The thirty is a long-term goal.

As for the no outbound capability, and any potential questions about 911, all users will know that outbound calls aren’t possible. Also, this is an Emergency Communications related project that I’m working on, so in theory, there will be a phone at the 911 Call Center, as well as local Police, Sheriff, and Fire. That’s far down the road though.

I’m not sure if it matters, but I’m putting the cart before the horse, so to speak. We don’t have any phones picked out yet, so if that’s a consideration in my questions, give me a worst-case scenario.

Thanks and have a great night. :slight_smile:

I think you need to re-visit that 911 regulation and understand it fully. It’s not a case of saying “you should have known you can’t do that”.

IANAL, but IMO none of the new 911 regulations apply to systems that do not connect to the PSTN.

For example, a door phone system in a condo building does not need to be able to dial 911, even though the lobby device may have a keypad resembling one on a telephone. Get legal advice if you are concerned.

A small system like yours would do fine with one NIC, though you may want one connected to the radios and one connected to the internet, as an easy way to gain some security. If the radios already have access to the public internet, I’d stick with one NIC to keep it simple.

A small PBX could get by with ~10 GB disk space, though you may want to record all calls, so consider what you’ll need for that (how much traffic, how long you want to keep recordings, etc.)


Space will depend on what you are storing. If you are keeping large, robust logs and call recordings, you might need a little more space, but we have used 16GB drives for lightweight systems with plenty of space left over.

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