Connect RTB calls over SIP — a SIP address on every reservation

Why this matters

When you ping our RTB endpoint and win a reservation, you need a way to route the live call to us. Until now, getting a routable destination back depended on the shape of your request and we were returning and inbound number to route the call to. Sometimes there was also a sip address.

Now every successful RTB reservation comes back with a SIP address you can dial to connect the call — no matter how you pinged us. Note that the publisher should be whitelisted with IP or username and password to successfully send the call.

What's new

Reserved (and confirmed) RTB responses now include a sip_address field alongside the inbound_number you already receive.

The SIP address is dynamic: it's unique to each reservation, so you always dial the exact destination tied to that specific call.

Most importantly, you get a sip_address back whether or not you provide a caller_number in your ping. Whichever way you reserve, you'll have a SIP target to connect to.

How to use it

Ping the RTB endpoint as usual. With a caller number:

curl -X POST "https://rtb.retreaver.com/rtbs.json" \
  -d "key=YOUR_POSTBACK_KEY" \
  -d "caller_number=+18888888888"

…or without one:

curl -X POST "https://rtb.retreaver.com/rtbs.json" \
  -d "key=YOUR_POSTBACK_KEY"

Either way, a successful reservation now returns sip_address:

{
  "rtb": {
    "uuid": "0c4d6f2a-1b3e-4a9d-8c7f-9e2b1a6d4f30",
    "status": "reserved",
    "retreaver_payout": 12.5,
    "retreaver_seconds": 60,
    "inbound_number": "+18005551234",
    "sip_address": "0c4d6f2a-1b3e-4a9d-8c7f-9e2b1a6d4f30@sip.rtb.retreaver.com",
    "expires_at": "2026-06-17T14:32:05Z"
  }
}

Dial the sip_address to connect the call over SIP, or keep using inbound_number to connect over PSTN — both point to the same reservation.

Access

The sip_address is returned only on reserved and confirmed reservations. Pings that don't result in a reservation won't include it.