How the Transfer Call tool works on SIP trunk calls: the target is dialled through your own trunk, the caller hears ringback, and a failed transfer ends the call.
On a SIP trunk call, the Transfer Call tool hands the caller to a person by dialling the transfer target through the same trunk. Your carrier carries the call to the target, so it is billed on your carrier account like any other call you place.
The agent decides to transfer, says the tool’s pre-tool message, and stops talking.
Bolna dials the transfer target through the trunk. The caller hears a ringing tone, and the agent stays silent.
When the target answers, the caller and the target are connected and the agent leaves the call. The call ends when either of them hangs up.
The target sees the trunk number on the call as the caller ID: the number that was called, on an inbound call, or the caller ID the agent used, on an outbound call.
A failed transfer ends the call. If the target is busy, declines, does not answer in time, or your carrier refuses the call, Bolna hangs up on the caller. The agent does not take the call back. Check that the destination is reachable through your carrier before you rely on it.
Through the trunk’s first gateway, the one with the lowest priority value. The number is sent with or without the + according to the trunk’s Dial with leading plus switch.
A SIP URI, for example sip:4001@sip.carrier.com
To the URI’s host, which must be one of the trunk’s gateway hosts. The port comes from the URI, or from that gateway when the URI has none. The user part may use letters, digits and + * # . _ -, up to 64 characters.
Bolna does not dial a SIP URI whose host is not one of the trunk’s gateways, so a transfer can only leave through your own carrier. A transfer is a single attempt on one gateway; it does not fail over to the trunk’s other gateways.
On the agent’s Tools tab, add Transfer Call and describe when the agent should transfer.
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Choose the destination
Under Transfer destination, choose Phone number and enter the number, or choose SIP trunk (URI) and enter a SIP URI on one of your trunk’s gateways. The SIP URI option is available once the agent’s Telephony Provider is SIP Trunk.
A SIP URI destination on a SIP Trunk agent
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Add headers (optional)
Under Custom SIP headers, add headers for the target’s INVITE. See Transfer-leg headers for the rules.
Ring time. The target rings for 30 seconds by default. To change it, set ring_timeout in the transfer tool’s param to a whole number of seconds from 1 to 120.
Channels. The call to the target uses a second channel on the trunk for as long as it lasts. If the trunk has no free channel, the transfer is refused.
One transfer per call. Once a call has started a transfer, the agent does not start another.
Bolna refuses a transfer without dialling anything when the destination is not reachable through the trunk (a SIP URI on another host, or a number that is not digits), when the trunk has no free channel, or when the trunk has no gateway. Nothing rings in that case. The agent no longer responds to the caller, and the call ends when the caller hangs up or the agent’s hang-up-on-silence setting ends it.
