Replacement technology for TAPI?

manpreet Best Answer 2 years ago

Is there a replacement technology for TAPI that supports third-party call control (3pcc)?

I want to provide the following 3pcc functionalities in an application:

1. Outgoing call:

   • User clicks at a button in the application.
   • The user's phone goes off hook, and the callee's phone rings.
   • The callee's phone shows the phone number of the callee, not the phone number used for the application.
   • When the callee picks up the phone, the connection is established.

2. Incoming call:

   • When user's phone rings, the caller's number and the called number are sent to the application.
   • The application evaluates the numbers and shows e.g. a customer record.

In the past, I would have done this with TAPI, but it seems that Microsoft does not actively develop TAPI any more (even though TAPI is supported with all current Windows versions, up to Windows 7). Therefore, I am searching for a technology that is more likely supported in the future by the majority of telephony system providers.

I am aware of CSTA, which could be used to do this, but this also is a pretty old technology and not very widespread (it has 100 times less Google hits than TAPI, for example).

I am also aware of SIP, which does not have direct support for 3pcc features, but there are ways to work around this:

• For outgoing calls: use application's SIP endpoint to connect to the two phones first, then connect them by making a kind of "conference call".

• For incoming calls: use SUBSCRIBE and NOTIFY and dialog event package.

Problem is that the procedure for outgoing calls is very clumsy, and the called phone would not display the correct phone number (i.e. the caller's number) when ringing. Furthermore, SIP is not a single standard, but a collection of many different RFCs, and it seems that telephony system manufacturers only implement parts of those RFCs, and there usually is no good documentation which parts are implemented.

So, my question is: is there any other telephony integration standard that supports third-party call control, and that can be considered as a widely supported standard in the foreseeable future?