Merge pull request #215711 from radubulboaca/master

add rooms call definition (plus Acrolynx fixes)

Author: prmerger-automator[bot]

articles/communication-services/concepts/voice-video-calling/about-call-types.md

@@ -26,7 +26,7 @@ When a user of your application calls another user of your application over an i
 
 ### Public switched telephone network (PSTN)
 
-Any time your users interact with a traditional telephone number, calls are facilitated by PSTN (Public Switched Telephone Network) voice calling. To make and receive PSTN calls, you need to add telephony capabilities to your Azure Communication Services resource. In this case, signaling and media use a combination of IP-based and PSTN-based technologies to connect your users.
+Anytime your users interact with a traditional telephone number, calls are facilitated by PSTN (Public Switched Telephone Network) voice calling. To make and receive PSTN calls, you need to add telephony capabilities to your Azure Communication Services resource. In this case, signaling and media use a combination of IP-based and PSTN-based technologies to connect your users.
 
 ### One-to-one call
 
@@ -36,11 +36,15 @@ A one-to-one call on Azure Communication Services happens when one of your users
 
 A group call on Azure Communication Services happens when three or more participants connect to one another. Any combination of VoIP and PSTN-connected users can be present on a group call. A one-to-one call can be converted into a group call by adding more participants to the call. One of those participants can be a bot.
 
+### Rooms call
+
+A call that takes place within the context of a Room. A Room is a container that manages activity between Azure Communication Services end-users. A Room offers application developers better control over *who* can join a call, *when* they meet and *how* they collaborate. To learn more about Rooms, see the [conceptual documentation](../rooms/room-concept.md). 
+
 ### Supported video standards
 We support H.264 (MPEG-4).
 
 ### Video quality
-We support up to Full HD 1080p on the native (iOS, Android) SDKs. For Web (JS) SDK we support Standard HD 720p. The quality depends on the available bandwidth.
+We support up to Full HD 1080p on the native (iOS, Android) SDKs. For Web (JS) SDK, we support Standard HD 720p. The quality depends on the available bandwidth.
 
 ## Next steps