Asterisk is modular and has so many incredible built-in applications. Modern day call centers require a lot of functionality and, Asterisk provides a contact center platform that is truly versatile, at tremendous cost savings. Live listening in Asterisk is an exciting feature for call center managers. Live listening is not new but Asterisk makes it much more accessible with its chan_spy. G729 is a popular codec (you can purchase G729 license from Digium) which reduces bandwidth consumption to around 45 Kbps per channel. When bandwidth costs are at a premium G729 can provide a 50% savings. Agent phones using G729 can minimize transcoding and reduce system load on Asterisk. Eyebeam, the licensed full featured version of X-lite, is a popular soft-phone with inbuilt G729 codec.
Indosoft call center software Q-Suite runs on Asterisk and we come across a variety of infrastructure variations in our contact center technology deployments. In one such installations which uses G729 for all its outgoing calls, the call center supervisor complained about calls getting disrupted every time they use snoop to perform live listening. We set up a test rig and tried to snoop into a SIP channel with Eyebeam G729 without realizing that the silence suppression was turned on. Many of the applications within Asterisk do not send packets unless they are receiving packets and Asterisk does not support silence suppression. Of course, this is bound to cause issues if the Eyebeam setting allowed silent suppression. Agent will stop hearing the other end when they are silent and listening. But the most interesting aspect is the way this issue gets reported by call center staff as ’calls getting dropped or cut-off’. It is important to make sure that the setting for silence suppression is left checked as shown in the screen-shot below. A similar issue with the default setting of call inactivity results in X-Lite dropping the the connection .
Silence suppression setting for Eyebeam
Efficient network setup can enhance the quality of your VoIP experience. Even if you are averse to VoIP terminations for routing long distance traffic, within your call center, you can take advantage of VoIP. Here is a simple but efficient topology for Asterisk based call center setup.
- Asterisk based contact center network layout
Here all the agents, supervisor and admin phones are within the LAN and have assured bandwidth. Good quality IP phones from Polycom, SNOM, Linksys and other vendors can serve as the admin phones. Agents can use softphones like X-Lite or Eyebeam. An enterprise grade call center software like Indosoft Q-Suite will provide all the necessary features to setup and manage an advanced contact center. I recommend DELL 2950 category of servers which has served as very well in the past. The Dell web managed switches are inexpensive and work well within the contact centers. We implemented our first VoIP based contact center using Asterisk in 2003 with the long distance traffic terminated on PRI using Digium TDM board.
2000:
The servers were all stacked on a table at the back of the main development room. In the picture, the entire network infrastructure for the company is present. There are 5 servers pictured:
- On the left, hidden is indoserv, the mail e-mail and web server
- On the left in front, is havana a dev/file server
- On the right, in behind is paris, a spare server
- On the right on front is london, the firewall
- On the right, under london & paris is cairo, the dial-in server
- To the right of the servers is a 700VA UPS, 16 port 10Mbps hub and the modem for cairo.
- Temperature control was provided by the in-window air conditioner
- A KVM was purchased shortly after this picture was taken
The only thing in that picture that is still in use is the table, which is now in Rajan’s office.
Compare it to today:
- 2 cabinets (older machines are tower servers and are on the shelves to the left)
- 8 UPSes
- 20 servers
- 2 16 port KVMs
- 5 24 port Gigabit switches (most are in a small rack attached to the wall and not in this picture)
- Temperature controlled by the 12,000 BTU mini split AC (we don’t have to worry about heating in the winter)
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