We built a proof of concept to allow video conferencing between 3 users using the AT&T calling services API. It was designed as a cross platform communication application and supports web browser usage as well as an iOS application built for both iPad and iPhone. Per the requirements of the POC, a user on either iOS or web browser can initiate a video conference call with two other users on either platform.
Though we encountered a number of challenges in development, we were able to get everything working.
By reviewing the API details provided, we were able to identify that the API supports direct video calling only between 2 users, and a user is not able to call multiple users.
As an example, we have three users: users A, B and C.
A calls B
A calls C
B calls C
A calls B and C
We therefore developed a work around. With the help of a 3-way mutual calling technique, we have made conferencing between 3 users possible, and the workflow is transparent to the users. With the workaround, A calls B and B calls C as indicated above, however the user interface when establishing the call gives the appearance that A is calling B and C.
A calls B and B calls C
Step 1
- A logs into the application as the host
- B and C log into the application as participants
Step 2
- A enters the primary contact ID for B and C and starts the call
Step 3
- A call from A to B is made
- B answers the call, and immediately a call from B to C is made
- C answers the call, and immediately a call from C to A is made
- A answers the call without any interaction
Through this workaround, we are able to accomplish the appearance of a 3-way video call
where under the covers we run three separate 2-way video calls.