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Which Telephony Interface for your Solution: VoIP Gateway VS PCI card?

What is your PBX or CTI solution without an interface to the outside world. One can use VoIP but there are still a lot of systems going the traditional route and connecting to a Telco either via Analog (POTS) or a T1/PRI/E1.  With Asterisk the two main solutions to do this are an internal PCI card or an external Gateway device. Both options will make and receive calls from the telco but which one is better?

I’ll cut to the chase and say PCI cards should not be recommended for High Availability solutions. They can still have their place in a system without HA and where costs are a major factor, but the decision to use them should be made with their limitations in mind.

Using a Gateway device, such as Patton or Audiocodes, provides the following benefits over an internal card:

  • Multiple telephony servers can connect to a single gateway. Which is important for the next two items.
  • With multiple servers connected to a single gateway in a HA solution calls will be routed to the active server(s).
  • Load balancing done at the gateway level in a high volume centers to distributed calls across servers.
  • Independence from a single server. If a specific server needs to be rebooted or taken offline for maintenance a gateway will keep working.
  • Location of telco demarc can be independant of telephony system. This can be in a different room, floor, building or even country. Just be careful of lag causing issues. But given the proper connections can allow moving the IP PBX system into the cloud while still supporting traditional telco trunks.
  • In a mixed trunk environment of VoIP and traditional telco connections the Gateway can abstract this so the IP PBX’s configuration is similar for all trunks.
  • Scaling up only requires adding a new gateway and a configuration change to the telephony system which minimizes downtime and risk.  Mainly due to avoiding the need to open the system to install new cards.

Considering the above it is hard to see the case for a PCI card, especially in an HA solution.  They may still have their place elsewhere but I’ll be recommending a VoIP Gateway going forward.

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The Differences in Call Survival and Call Recovery

While investigating High Availability (HA) in CTI and PBX systems you will often find mention of Call Recovery. Another term you run into is Call Survival, which is often used interchangeably with Call Recovery incorrectly. This is because each is a different approach to solving a problem. The problem being a failure which would interrupt the calls of a system.

With Call Survival when a failure happens the caller and callee do not have to take action to continue their call as it survives the failure. At a high level this is done by reacting to the failure quickly and re-routing the audio path around the failure.

With Call Recovery when a failure happens the recovery is different depending on the system. Sometimes the caller will need to initiate the redial the callee or it could be an automated process but the callee still have to answer this new call.

From a user perspective the better option is Call Survival as they may only experience a momentary interruption in their audio as the path is rerouted around the failure instead of having to re-initiate a call to recovery it.

The Q-Suite platform supports Call Survival with the help of the Overseer Watchdog providing HA for other services in addition to being one part of the Call Survival solution.

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Contact Center ACD interface through Asterisk Manager Interface (AMI)

Large contact center installations with many concurrent users will scale to multiple Asterisk servers. This is the norm when building out a multi-tenant contact center or PBX roll out. With the growing popularity of Asterisk, it is being adopted for special mission critical applications with large concurrent users. In all such applications, the call center ACD plays a vital roll in managing queues and users. It routes the calls in the queues to the appropriate user console based on skills based routing and queue prioritization.

For more dynamic applications, the console application would want to have the real-time status information of all the calls in the queues. This data provides an opportunity to build additional powerful logic in the user consoles to better manage the calls. Such user consoles for customer service representatives and supervisors can empower them to intervene and handle calls based on the business rules of the organization.

A contact center ACD will manage multiple Asterisk telephony servers in a cluster through the Asterisk Manager Interface. Console applications can have continuous feed of the dynamic channel status information from all the incoming and outgoing calls handled by the call center ACD, by incorporating a listener in the console software. With adequate filters, this listener can be tuned to feed data to a versatile call handling logic, taking advantage of the real-time state information of all the channels, queues and users of the call center software.

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Multi-channel ACD in a Cloud setup

Cloud is the new frontier for voice telephony and the contact center ACD (Automatic Call Distribution). The convergence of the transport mechanism for Voice with Data through Internet Protocol (IP), the acceptance of Session Initiation Protocol (SIP) as the default standard for Voice over IP (VoIP) transmission, and the consolidation of infrastructure accessible through Internet, have created a favorable environment for the growth of ‘Cloud’ based contact services.

Depending on the size and scale of a contact center operation, there are some options on how best to migrate to the Cloud. The larger operations can move to managed services in a Cloud platform where they exercise control over the operation without actually owning all the infrastructure. The smaller operations can be a part of a multi-tenant installation that is segmented and partitioned to provide an exclusive setup. Both these options provide a number of advantages including lower cost of setup and operation as well as the ability to have a geographic distributed work-force.

A multi-channel ACD handles more than voice. The additional channels may handle Chat. Email, and Social media. The ACD serves to distribute the conversations based on skills based routing but the media in the individual channels are handled by the respective media server. In the case of voice communications, the media server is the PBX switch. Asterisk dominates this category as a hybrid PBX which works seamlessly with both VoIP and the traditional Time Division Multiplexing (TDM).

The underlying technology stack for setting up multi-channel contact center ACD does not differ very much between a premise installation or a data center installation in the Cloud. With a competent hosted service provider to offer managed services, this can dramatically reduce the associated Information Technology (IT) operational cost. Also, sites with good connectivity offer the ability to have geographically distributed and remote agents. Some contact center software are multi-tenant by design and this enables the hosted service provider to offer shared IT resources for its tenants, thereby lowering the overall operational cost.