At least some embodiments, a system includes a memory, and a processor configured to convert an audio stream of a speech of a customer during a customer call session into customer-originated text. The customer-originated text is displayed in a first chat interface. A request from a first call center agent is sent to a second call center agent via the first chat interface to interact with the customer during the customer call session and displayed in a second chat interface. The second agent is allowed to participate in the customer call session when the second call center agent accepts the request from the first call center agent. First agent-originated text and second agent-originated text during the customer call session is merged to form a combined agent-originated text and synthesized to computer-generated agent speech having a voice of a computer-generated agent based on the combined agent-originated text communicated to the customer over the voice channel.