Omnichannel, plainly.
Omnichannel is not a channel list. It is an operating commitment: every customer-facing conversation, on every surface, runs on the same record, the same tone, and the same resolution standard, in the language the customer reached out in. The customer arrives on voice, follows up on chat, gets an email the next morning, opens a ticket the next day, and DMs on social a week later. The program holds the thread, or the customer holds a grudge.