About Direct Line


The Bot Framework offers multiple channels with the Direct Line branding. It's important that you select the version that best fits the conversational AI experience you're designing.

  • Direct Line. This is the standard channel offering of Direct Line. It works by default with bot templates via the Azure portal, bots from the Bot Builder Samples, and bots created with the Azure CLI. This is the Direct Line best suited in the majority of the cases. See Connect a bot to Direct Line.
  • Direct Line Speech. It provides text-to-speech and speech-to-text services within the channel. It allows a client to stream audio directly to the channel which will then be converted to text and sent to the bot. Direct Line Speech can also convert text messages from the bot into audio messages spoken by an AI-powered voice. Combined, this makes Direct Line Speech capable of having audio only conversations with clients. See Connect a bot to Direct Line Speech.
  • Direct Line App Service Extension. It runs inside the same subscription, App Service, and Azure network as your bot. If you have network isolation requirements, this version of Direct Line may be ideal. Bots and clients require special modifications to work with the Direct Line App Service Extension to ensure traffic never leaves the isolated network. See Direct Line App Service Extension.

You can choose which offering of Direct Line is best for you by evaluating the features each offers and the needs of your solution. Over time these offerings will be simplified.

Feature Direct Line Direct Line App Service Extension Direct Line Speech
Availability and Licensing GA GA GA
Speech recognition and text-to-speech performance Standard Standard High performance
Supports legacy web browsers Yes Yes Yes
Bot Framework SDK support All v3, v4 v4.63+ required v4.63+ required
Client SDK support JS, C# JS, C# C++, C#, Unity, JS
Works with Web Chat Yes Yes Yes
VNET No Yes No

Additional resources