I see Asterisk as the best thing to hit telephony since the rotary dial! Instead of buying extremely overpriced proprietary hardware, you can get more standardized phones and equipment, and customize to your heart's content. Our office uses T1 comming in as Hdsl2 to our smart jack, then to Asterisk through the TDM card, then out to the Grandstream phones in the office, then IAX to my home and the old 1A2 key system. For us VOIP is a blessing, and has saved me so much money because some employees can work from home when getting sick or stuck at home for other reasons. The T1 service saves us money versus the 6 analog lines we had. Yes we have had some problems but I appreciate being able to learn more about our phone system and being able to make changes myself.
On the other hand one of our suppliers switched to a "hosted" pbx system. This was a disaster as call quality was low, and when the network goes down so does the phones. With us we have two analog backup lines and an analog fax line just in case, they has no redundancy. VOIP is the best thing to hit telephony in my opinion, but when its limits are not considered things end up badly. Our supplier switched from hosted PBX to TDM and have not looked back.
I still enjoy hearing my phones RING with real bells, and being able to do business in my 50's style home office, thanks to VOIP. Now if I can replace my ATA boxes with a channel bank so I can dial with the rotary phones....
