At a bank or a large telco, this is not a chronology; these are layers in the stack.
The billing system still runs on the mainframe. There’s still a service provisioning system bolted onto the ERP. CRM is how the sales and customer support teams interact with those backend systems, and now there’s chatbots (some of which are LLM powered) on top of the CRM handing some routine customer interactions.
If you look at IT history, it goes something like: