reply to PToN
Re: VoIP system Couple quick notes:
Original Cisco phones used a proprietary PoE scheme (original 7940's come to mind).
Every Dlink/Linksys PoE switch I have used has burnt up - no exceptions. I'm not talking one or two either, i'm talking on the magnitude of 20-30.
I do like the Cisco IP Phones. I find that they work well with Cisco switches. No experience with them and HP switches, or HP switches in general.
Used Cisco phones can be had cheap online (ebay). In newer (version 6, IIRC) you will require a license for each phone - something NOT included with the purchase of CUCM (Cisco Unified Call Manager).
Cisco is expensive. Very expensive. I use it daily. I like it but I am also fond of asterix.
I will modify lorennerol's quote: SIP trunks will only work, reliably, with less than 4 trunk channels at any given time. I had a client with around 14 and a 100MB internet connection. They always had problems when they had 6+ people on the line. We switched to a provider based SIP trunk from the ISP. Problems solved.
You say 200 employees....how many phones? Smaller deployments may work with CUCMX (Cisco Unified Call Manager Express), which is hosted entirely within an ISR router.
Here's the problem with Cisco: You need a Cisco company to give you a quote. You are NEVER going to figure out the acronyms or this version that or licensing by yourself.
The VERSIONING and what is compatible with what is ABSOLUTELY ridiculousness. You also have upgrade paths. 4.x and 5.x can go to 8.X., 7.1 cannot but 7.1.3b can, etc.
And lastly: Asterix and Cisco (two I have used) are all "piecemeal". They have MANY MANY products which were separate crammed into one "solution". Cisco's used to be horrible. To add an extension for voicemail in 4.x (very old now), was two programs and three (different) websites.