How do I route English and Spanish speakers to the right AI agent on inbound or outbound calls?

There are several ways. Pick the one that fits your business.

Forward to agent node: add a Forward to agent node and select the agent the call should go to, for example a Spanish agent with a Spanish voice.

Global node: if you do not know when a caller will ask for Spanish, turn a conversation node into a global node and give it a title such as Spanish agent. Add the instruction: any time someone wants to speak with a Spanish representative or speaks Spanish, go here. The AI jumps off the normal path to that node, can say a short line such as one moment while I transfer your call, and then forwards to the Spanish agent.

Language field with a Decision node: store a custom field such as Language on the contact. Add a Decision node (it works for inbound and outbound) with an English option and a Spanish option where Language equals that value, plus a No match branch. English goes to the normal English greeting, Spanish forwards to the Spanish agent, and No match (for example a first-time caller you know nothing about) asks the caller whether they prefer English or Spanish and then sends them down the right branch.

One agent that speaks both: pick a Spanish voice that can also speak English and let one agent handle both languages, with no transfer. If the agent uses an English voice, use a transfer line such as one moment while I transfer you to a Spanish speaker, and forward to a separate Spanish agent.

An English voice saying a Spanish word in a greeting will sound like a non-native speaker. Use a Spanish voice, or record your own audio message and play it so it is read exactly the way you want. The pronunciation settings can also help.