A customer calls, gets cut off, and messages on WhatsApp. In most contact centres that is two tickets, two agents, and one person repeating themselves. The architecture decision that prevents it is older and duller than any AI feature: everything enters through one system, and identity belongs to the customer rather than the channel.
One mandatory entry point
If any channel can bypass the interaction layer, the timeline is incomplete, routing rules see a partial picture, and the audit trail has holes. Making the entry point mandatory is unglamorous and it is what makes everything downstream trustworthy — the history an agent sees, the context the AI reasons over, the numbers in the report.
Channel adapters, not channel products
A channel should be an adapter at the edge that normalises an inbound message into a common interaction shape, and nothing more. Business logic never lives in the adapter. That constraint is what lets you add a channel without rebuilding flows: the routing, the knowledge, the quality scoring and the reporting were never written against WhatsApp in the first place.
Voice is the honest test
Text channels are similar enough that a mediocre architecture survives them. Voice is where the shortcuts show: different latency budget, streaming rather than discrete messages, a transcript that arrives progressively, and a hand-off that has to happen while the customer is still on the line. A platform that treats voice as a first-class interaction rather than a bolted-on telephony integration behaves very differently under load.
Why this is an AI question now
A model is only as good as the context it is handed. If the customer's last three interactions were on three channels and the platform cannot assemble them into one history, the AI starts every conversation uninformed no matter how capable it is. Channel-agnostic architecture is not a convenience feature; it is the input quality problem for every AI decision that follows.
One AI brain across every channel is, in practice, a data statement before it is a model statement.