Applies To

Call2Teams - Customers


When a user transfers a call, the call drops. The target recipient is left on hold.

The problem seems to be related to Consultative transfers.

Call Transfer Overview (Ideal Behavior)

When the initial call is established between Party A and Party B a direct link is created called a call leg.

When Party B makes a consultative/enquiry call to Party C, Party A is placed on hold.

The new call leg between Party B & Party C is established.

When the transfer key is pressed, SIP messages are exchanged which advise all systems to join Party A from call leg 1 to Party C of call leg 2. 

This is done by creating a third call leg. 

Once established, call legs 1 and 2 are terminated as these are no longer needed.


With Party C connected to a single call leg (talking to Party B), they must be able to receive a second call invite (leg 3). 

This relies on Party C being able to receive call waiting (a queued call) on their line which is not always possible, especially if Party C is a regular PSTN user. 

If they cannot accept the new call before the other 2 call legs are dropped, then the final 3rd call leg cannot be created and the call will drop. 

This can result in one or more of the affected parties unable to complete their calls.


The service offers the ability to modify how the SIP REFER message works, via the Propagate Refer setting in the PBX/Trunk settings page in the service portal:

This setting provides 3 options:

  • PBX handles transfers will propagate received SIP REFER messages from Microsoft upstream to this service.
  • Teams handles transfers will manage transfers bridged out as new calls.
  • Teams True Transfer is designed to operate where both the transferor and the transferee are connected to the PBX service.

When using Teams True Transfer mode, a call is transferred directly within Teams to another Teams user, and the call is also transferred in the background to the destination user on the PBX.

This mode offers the following benefits:

  • It provides correct off-hook busy representation of both users after a transfer
  • It enhances the attended transfer experience for users, especially where transferring to a call queue agent
  • Users are free to take another call following a transfer 
  • It ensures compliance, integration, reporting and recording is applied to the correct agent
  • It means both the user’s SIP phone and PBX Voicemail will ring and be active following a Teams-to-Teams transfer

Teams True Transfer is recommended for multi-agent queues and Call Center environments.

Note: Teams True Transfer should not be used in environments where a large number of users are not connected to the PBX as the transfer to another Teams user will not complete satisfactorily. 
In these scenarios it is recommended to use one of the alternative transfer modes listed above.

Issue: Consult Transfer Failures using Jabra Headsets

In some cases, following a consultation call, a transfer may not complete successfully, leaving the consultee connected to the original call where Jabra headsets are used. This appears to be a third-party issue.

Follow this link to learn more: Jabra headsets staying connected after consult/transfer


Please note Dstny Automate cannot be held responsible for the content of any third-party documentation offered.