Control the call flow from within your agent. End calls gracefully or transfer to a human.
Ending Calls
Use SDKAgentEndCallEvent to end the call:
from smallestai.atoms.agent.nodes import OutputAgentNode
from smallestai.atoms.agent.events import SDKAgentEndCallEvent
from smallestai.atoms.agent.tools import function_tool
class MyAgent(OutputAgentNode):
@function_tool()
async def end_call(self) -> None:
"""End the call gracefully."""
await self.send_event(SDKAgentEndCallEvent())
return None
Tools that send SDK events must use await self.send_event() and return None. Simply returning the event object won’t work.
Transferring to Humans
Use SDKAgentTransferConversationEvent to hand off to a human:
from smallestai.atoms.agent.events import (
SDKAgentTransferConversationEvent,
TransferOption,
TransferOptionType
)
from smallestai.atoms.agent.tools import function_tool
class MyAgent(OutputAgentNode):
@function_tool()
async def transfer_to_human(self) -> None:
"""Transfer to a human agent."""
await self.send_event(
SDKAgentTransferConversationEvent(
transfer_call_number="+14155551234",
transfer_options=TransferOption(
type=TransferOptionType.COLD_TRANSFER
),
on_hold_music="relaxing_sound"
)
)
return None
Transfer Parameters
| Parameter | Type | Required | Description |
|---|
transfer_call_number | string | Yes | Human agent’s phone (E.164) |
transfer_options | TransferOption | Yes | Transfer type |
on_hold_music | string | No | "ringtone", "relaxing_sound", "uplifting_beats", or "none" |
Transfer Types
from smallestai.atoms.agent.events import (
TransferOption,
TransferOptionType,
WarmTransferPrivateHandoffOption,
WarmTransferHandoffOptionType,
)
# Cold transfer (immediate handoff)
cold = TransferOption(type=TransferOptionType.COLD_TRANSFER)
# Warm transfer (agent briefs human first)
warm = TransferOption(
type=TransferOptionType.WARM_TRANSFER,
private_handoff_option=WarmTransferPrivateHandoffOption(
type=WarmTransferHandoffOptionType.PROMPT,
prompt="Customer calling about billing"
)
)
Call Flow Events
When these events trigger, they appear in call logs:
| Event | Log Entry |
|---|
SDKAgentEndCallEvent | hangupSource: "agent" |
SDKAgentTransferConversationEvent | transferTarget: "+1..." |
Tips
Tell the user before transferring: “I’ll connect you to…”
Use cold transfer for simple handoffs
Faster than warm transfers.
Say goodbye before ending, don’t just hang up.
Have a general transfer number if specific departments unavailable.
