The SILM feature allows executives or supervisors with sufficient privileges to silently listen to an audio call or conference that a subscriber to be monitored participates in. Once in a silent monitoring session, the executive or supervisor can either barge into the conversation (via CSTA) or terminate the monitoring without affecting the ongoing conversation. It is also possible to barge in without prior "passive" monitoring.
The target subscriber is not informed about being silently monitored during the lifetime of the call. This might be prohibited by applicable law.
A subscriber can't monitor more than one subscriber at a time. Conversely, a call (or conference) can have no more than two monitoring subscribers. If a third subscriber attempts to monitor the same call, a rejection is played back to the monitoring device.
SILM activation and barge-in can be performed using Feature Access Codes or via the CSTA Interface:
from the monitoring/recording device (a SIP endpoint from Lotus Sametime Unified Telephony's perspective) using preconfigured Feature Access Codes and the destination to monitor (e.g. *72#<DN>#).
This is the preferred mode of on-demand monitoring/recording.
from a CSTA application using the Join Call Service, Change Connection Information and Clear Connection requests. The first allows to join the monitoring/recording device to a call to be monitored, the second allows toggling between passive and active monitoring and the third is for terminating the monitoring.
This is the preferred mode of application-controlled monitoring/recording.
Note that Silent Monitoring of an unified number subscriber requires the CSTA variant.
The SILM service shall make use of the following information to allow device monitoring:
- both monitoring subscriber and monitored subscriber reside on the same Lotus Sametime Unified Telephony switch and within the same BG
- SILM is enabled at the BG level
- the monitoring subscriber is provisioned with the SILM service
- the subscriber to be monitored is not protected from monitoring
- the subscriber to be monitored is in a stable call and this call is not already being monitored by more than one subscriber
SILM may fail for a number of reasons, including bandwidth limitation, media server resources, execution of call control services that do not interact with Silent Monitoring. In any case, the original call is not affected and the monitoring device is played a prompt or an error tone and is dropped gracefully.
The Role of the Media Server
The monitored call will be mediated through the media server:
monitoring a basic call requires three conference connections, one for each of the device in the call and the third one for the monitoring entity.
monitoring a conference calls requires one additional connection on behalf of the monitoring entity.
Call Detail Records
Call Detail Records are updated to indicate a call between the monitoring device and the monitored device when the monitoring is successful. If the Join Call is executed via unified number addressing, CDR shall indicate the unified number leg of the call.
Parent topic: Mobility and Collaboration
On-demand and Continuous Recording
SILM can also be used for on-demand and continuous recording of conversations and (encrypted) conferences.
SILM Service Provisioning
The SILM service has to be provisioned both at the BG (Business Group) and at the subscriber level. Furthermore, the Feature Access Codes for monitor/barge-in have to be created in the affected numbering plans and/or CSTA has to be activated for the monitoring subscribers.
Feature Access Codes for SILM
Feature access codes enable subscribers to start SILM (Silent Monitoring) or barge in to an existing call or conference from their endpoints. A feature access code can either be dialed or it can be assigned to a function key on the subscribers' phones, providing seamless access to server-side features.