Trunk between call center and avaya. Maybe someone has manuals?

Question

Avaya

Good day. There was a task: you need to connect the automatic telephone exchange and the call center, which will work as a secretary.
In short, how it will work: The call arrives at my avai, works out the voicemail, then jumps to the extension in the KC, and from there, by extension, whoever needs it. The biggest problem is that I have never done this.
I read the manuals:
Created a sipline, entered ip/log/pass into it, created a sip extension. It doesn’t work - it’s understandable, in the manuals (for example, in this https://max-komi.blogspot.com/2017/04/avaya-ip-off... ) the PBX is understood and the manager is much newer - I have IO403 and Manager R5 which lack most of the features. I would be grateful if you could help set up / poke into the guide.
Thanks in advance for your replies.