Limitations of ISDN call transfer

There are some limitations associated with using ISDN call transfer with Blueworx Voice Response. These limitations are:

• The two calls involved in the transfer (the original inbound call and the outbound call to the third party) must be connected to Blueworx Voice Response from the same switch. The Bellcore specifications allow the two calls to be on different trunks, provided that both trunks support ISDN Two B-channel transfer. The same is true for Nortel’s ISDN RLT call transfer.

  If the Blueworx Voice Response system has a mixture of CAS and ISDN trunks, the user application should ensure that the outbound call is made on the correct trunk for an ISDN call transfer to be successful.

  Note: The Nortel DMS-100 switch at release level NA008 permits a transfer only if the two calls (inbound and outbound) are on the same trunk. This must be taken into account when writing your application.
• No user access is given to the information elements on the transfer.
• ISDN call transfer is not totally compatible with the Blueworx Voice Response signaling model, so application changes may be required when porting applications that involve transfer operations from different telephony configurations. This applies mainly if you want to perform a third party consultation during a screened transfer operation.
• ISDN RLT blind transfer is not supported.