Voice Call

Overview

Voice call simply allows the control of a voice telephone call between two individuals. With the Web21C Voice Call Service, you can place calls between two individuals, access information about the call and end the call programmatically.

Features

The Web21C Voice Call Service currently provides the following features:

SIP & PSTN Gateway - Allows you to connect two participants anywhere in the world using a combination of the following; Traditional land line (PSTN), cellular or softphones (SIP). Voice Call, calls the first person and after being answered, calls the second person.
Statistical - Allows you to obtain call state and call duration information.
Pre-call announcement - the caller is played the following announcement: "Hello. You are being invited to a telephone call. Please press '1' to continue.". If the caller presses '1', the callee is called. (Note - the callee does not hear any announcement).
Announcements - are available in multiple languages and voices:
- 1:English female 1
- 10:Spanish male
- 20:Italian male
- 30:Polish male
- 50:Greek male
- 60:French female
The following announcements have been deprecated (as they mention the BT Web21C SDK) but are still available for use:
- 2:English female 2
- 3:English male
- 40:German male
The caller has 30 seconds to "Press 1" - otherwise the call is terminated. It is possible to "Press 1" while the announcement is playing.
CLI Blanking - Instead of sending a phone number to the participants in a voice call, the CLI is blanked, so they get "Number Unavailable".
Automatic refund - if either party does not "Press 1", the call is terminated and credits are refunded.

Note:

Calls to UK premium numbers, as regulated by ICSTIS, are blocked, as are other premium rate numbers worldwide.

The list of blocked numbers can be updated without giving notice, where such numbers allow customers to exploit arbitrage opportunities in our pricing. The Web21C SDK services are not intended to be used for medical emergencies, satellite communications or other specialist purposes.

Calls are limited to a maximum of one hour, after which they will be terminated.

Call information that is available to client applications is accessible for a period of 3 days.

Applications

The Web21C Voice Call Service allows programmatic control of voice calls. The Voice Call Web Forms component could be used, for example, to enable a feature on a website that calls people back when they leave a telephone number and request a call back. For example, you could use this service to create a distributed call center.

The Voice Call Service is used in the Voice Call sample application, which is available as part of the Web21C SDK in the Downloads page. To go there, please click here.

Note: Use our free virtual phones to test your applications work, please click here.

Code Example: (C#, using the Windows Forms component)

//Use the Web21C Voice Call Service to make an audio call between two telephones
//In a single line of code.

//Drop a Voice Call component onto your form from the Toolbox
voiceCall1.StartCall("tel:44123456789", "tel:44987654321");

//In this case, 44 represents the country code and the telephone number follows

References

.NET API Documentation