Omnichannel
Omnichannel means a receptionist handles conversations across several channels (phone, in-browser voice, SMS, email, chat, a customer portal, webhooks) with the same knowledge and the same record of the customer.
Also called: multichannel, cross-channel
Multichannel means being reachable in several places. Omnichannel is stricter: the channels share one brain and one history, so a customer who calls, then texts, then emails is one conversation to the business, not three tickets.
For a receptionist that implies a single persona and call flow reused across channels, a shared contact record, and the ability to continue a conversation on a different channel, confirm a booking by SMS after a call, say.
The practical test is whether the business meets customers where they already are, rather than requiring them to phone.