Telephony Resource Management
The fundamental challenge in implementing a telephony architecture for predictive dialing support is real-time resource allocation and deallocation. Resources in this context are trunk lines, stations and dialing ports (either dummy stations or DSP resources).
Softdial CallGem™ provides 2 different schemas, as follows, for ensuring that Softdial CallGem™ only uses telephony resources that are actually available.
CTI Schema 1
Softdial CallGem™ will assume that immediately on receipt of a command to dial a number or hang up a call, relevant resources are allocated or deallocated. Under this schema it will be necessary for the telephony layer to delay or buffer requests if the resource has not yet freed up. How this works in practice is as follows:
- Assuming there is a connected call on a trunk line and the agent has completed their transaction, Softdial CallGem™ will issue a Call Disconnect [CD] message to the telephony layer.
- Softdial CallGem™ will then assume that there is an additional trunk available to dial on immediately at the point where the disconnect is issued, and may initiate another call at that point.
- Meanwhile, the trunk may not have been disconnected. It can sometimes take a second for the PSTN to release the call and return the trunk state to idle. Until this happens a new call cannot be placed. So in this scenario it is necessary for the telephony layer to queue the call initiate request until the PSTN has released the previous call.
This situation also applies to stations (particularly analog stations) and to dialing ports (should they exist).
This schema has been the standard for all integrators until now. It has suited most business partners and has been economical of message traffic.
To Implement Schema 1:
To implement a telephony layer using this schema, request buffering is required. You will need to do the following things in addition to providing support for the general telephony layer messages:
- Do not implement support for the Now Disconnected [ND], Station Disconnect [SD] and Port Free [PF] messages.
- On receipt of a Call Initiate [CI] message, if there are no trunk lines available, queue the request until the next trunk is released.
- On receipt of a Call Transfer [CT] message, if the station has not yet been released, queue the transfer. You should only queue for a very short period of time.
- As an alternative to queueing the call transfer, you may elect for the application layer to request that the call is disconnected and then delay the Start Wrap [SW] or Transaction Complete [TC] message by a short period of time (a few hundred milliseconds) in order to make sure the station is freed up before returning the agent to the predictive pool.
- If your telephony solution uses dialing ports, Softdial CallGem™ will assume that a port is in use from the time the call is initiated until Softdial CallGem™ receives a Line Connected [LC] message. If DSP resources or dummy analog stations are used the dialing port will take a finite amount of time to be released. In this case you should consider delaying the Line Connected [LC] message by this period of time.
This potentially causes delays between the called party picking up the telephone and being connected with an agent. The delays may only be 500 milliseconds but they have a material impact on whether the solution will comply with the DMA regulations governing predictive dialing. In order to ensure compliance you should notify Softdial CallGem™ of the elapsed time between the called party going off hook and sending the Line Connected [LC] message to Softdial CallGem™. The Line Connected [LC] message has an optional parameter Offhook Delay [OD] to allow you to do this.
CTI Schema 2
With Version 8, we introduced an extra layer of functionality to Softdial CallGem™. This allows an exchange of information, so that no actions are initiated to deploy resources until responses have been given indicating that the resources are in fact free.
As in Schema 1, Softdial CallGem™ will assume that resources are allocated when a request is made by Softdial CallGem™, but it will wait for the telephony layer to notify it that the resources have actually been freed.
In this way Softdial CallGem™ will never make requests that consume resources not yet available.
Consider our scenario described above in Schema 1, where there is a connected call and the agent has completed their transaction.
- If the trunk line has not yet been released, Softdial CallGem™ issues a Call Disconnect [CD] message but does not change its internal trunk count.
- When the PSTN has released the call the telephony layer sends a Now Disconnected [ND] message. Softdial CallGem™ at this point assumes that there is an additional trunk available to dial on.
- Also, the agent is not released to the predictive pool until the telephony layer has sent notification that the station is idle.
To Implement Schema 2:
- For live calls:
To implement a telephony layer using this schema, supporting trunk, station and port negotiation, you need to ensure that you can get live call disconnect notifications from the network. Make sure you implement support for the Now Disconnected [ND], Station Disconnect [SD] and Port Free [PF] messages, using the relevant parameters in the and Trunks Open [TO] message. - For failed calls
These negotiations are unnecessary.