What IP addresses do I need to add to my firewall?
What IP addresses do you use to send requests to my MO or DLR webhook URL?
Can I use a firewall and still receive inbound requests from you?
I am not receiving callbacks to my HTTP server. Why might this be?
If you are restricting inbound traffic (including delivery receipts), please whitelist the following subnets:
18.104.22.168/28 (22.214.171.124 - 126.96.36.199)
188.8.131.52/28 (184.108.40.206 - 220.127.116.11)
in your firewall.
Inbound SMS traffic from Nexmo might come from any of the IP addresses included in the referenced subnets.