A method comprising: at an electronic device with a display: displaying a messaging user interface of a messaging application, the messaging user interface including: a message region including a plurality of messages between participants in a message conversation that includes three or more participants; and an affordance separate from the message region for starting a live video communication session in a live video communication application; detecting an input corresponding to selection of the affordance; in response to detecting the input corresponding to selection of the affordance, initiating a process for starting the live video communication session in the live video communication application, the live video communication session including the participants of the message conversation, wherein initiating the process for starting the live communication session in the live communication application includes, displaying a group contact user interface, the group contact user interface including a group contact affordance for starting the live communication session, detecting an input corresponding to selection of the group contact affordance for starting the live communication session; and in response to detecting the input corresponding to selection of the group contact affordance for starting the live communication session, starting the live communication session in the live communication application; and after starting the live video communication session: in response to a determination that a first participant has not joined the live video communication session for a predetermined period of time, displaying a reminder option that is associated with the first participant in the group contact user interface; while displaying the reminder option that is associated with the first participant, receiving an input corresponding to selection of the reminder option; and in response to receiving the input corresponding to selection of the reminder option, sending a notification indicating that the live video communication session is available to the first participant. displaying a messaging user interface of a messaging application, the messaging user interface including: a message region including a plurality of messages between participants in a message conversation that includes three or more participants; and an affordance separate from the message region for starting a live video communication session in a live video communication application; a message region including a plurality of messages between participants in a message conversation that includes three or more participants; and an affordance separate from the message region for starting a live video communication session in a live video communication application; detecting an input corresponding to selection of the affordance; in response to detecting the input corresponding to selection of the affordance, initiating a process for starting the live video communication session in the live video communication application, the live video communication session including the participants of the message conversation, wherein initiating the process for starting the live communication session in the live communication application includes, displaying a group contact user interface, the group contact user interface including a group contact affordance for starting the live communication session, detecting an input corresponding to selection of the group contact affordance for starting the live communication session; and in response to detecting the input corresponding to selection of the group contact affordance for starting the live communication session, starting the live communication session in the live communication application; and after starting the live video communication session: in response to a determination that a first participant has not joined the live video communication session for a predetermined period of time, displaying a reminder option that is associated with the first participant in the group contact user interface; while displaying the reminder option that is associated with the first participant, receiving an input corresponding to selection of the reminder option; and in response to receiving the input corresponding to selection of the reminder option, sending a notification indicating that the live video communication session is available to the first participant. in response to a determination that a first participant has not joined the live video communication session for a predetermined period of time, displaying a reminder option that is associated with the first participant in the group contact user interface; while displaying the reminder option that is associated with the first participant, receiving an input corresponding to selection of the reminder option; and in response to receiving the input corresponding to selection of the reminder option, sending a notification indicating that the live video communication session is available to the first participant.