If we had to pick the most significant trend in networking today, the VoIP phenomenon might well top the list. And open source is playing no small part. While enterprises remain reluctant to rip out their tried-and-true PBXes, open source VoIP -- usually in the form of Asterisk -- is capturing business communications one small business or branch office at a time. Sooner or later, enterprises too will catch the open source VoIP bug. The cost savings and flexibility are too compelling to resist.