Asterisk

Recently I've deployed three Asterisk based VoIP servers. I've used Trixbox ISOs, as I had good experiences using Asterisk@Home a few years ago.

In general, things have gone well. Here's a few things I've come across:

Asterisk in VMWare is far from ideal. I've had a lot of problems with quality and the start of audio being clipped off. This perhaps is as much due to my massively overloaded server as anything else.

Trixbox 2.2 (the current release) is based on CentOS 4.5, which is RHEL4 and runs Linux kernel 2.6.9. The hardware support is far from up to date - if you have something like a newer cheap SATA controller you'll probably lack support - while it'll claim Linux compatibility due to drivers being in the latest kernels. As a side note, modern cheap IDE and SATA controllers tend to be rubbish anyway. Never use onboard software RAID, the bugs and issues I've seen are great and varied.

VoIP phones are immature. They really are. You have the high end Cisco which is solid and performs brilliantly with Cisco servers, yet is virtually useless with the SIP standard due to bugs and generally piss-poor implementation. Then you have the cheaper phones which will actually work (hooray!) but be of such low quality that you wonder why you'd bother. And there are things like what might be nice features included in the firmware which simply don't work (case in point: Snom/Elmeg IP290. Pops up a VMail link when there's voicemail, but tried to open the wrong SIP URL, and is NOT configurable in the web interface with the rest of the config options - I later find an Asterisk-side workaround which gets this working).