I went to KnB Umeda event where they showed some parts of the Ikebukuro event as well. They also showed some conversations, and there’s one where Akashi and Kuroko had a short phone call. The setting for the event itself is Akashi sending a text to GOM (and invite Kagami, Takao, Himuro) to gather at Ikebukuro.
Akashi: Hello. Ah, Kuroko.
Kuroko: Akashi-kun. Have you already arrived at the meeting point?
Akashi: No. I finished my errand earlier than expected. I had some time, so I’m talking a walk (around the area) right now.
Kuroko: I see. By the way Akashi-kun, what is going on today?
Akashi: Fufu. You will see when you reach the place. Well then, until we meet in front of “Ikefukurou*”…
*note: Ikefukurou is the owl statue in Ikebukuro station. It’s a play of words from “Ikebukuro” (city name) and “Fukurou” (owl in Japanese).