# SMS Acknowledgement on Backup Gateway **URL:** \ **Category:** Ignition\ **Tags:** perspective\ **Created:** [September 18, 2026, 6:07pm UTC](https://forum.inductiveautomation.com/t/sms-acknowledgement-on-backup-gateway/117132 "2026-09-18T18:07:55Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![bpomerhn](https://avatars.discourse-cdn.com/v4/letter/b/41988e/32.png) [@bpomerhn](https://forum.inductiveautomation.com/u/bpomerhn)\ **Post date:** [September 18, 2026, 6:07pm UTC](https://forum.inductiveautomation.com/t/sms-acknowledgement-on-backup-gateway/117132/1 "2026-09-18T18:07:55Z")
Has anyone encountered an issue with acknowledgement of alarms via SMS not working when on a backup gateway? Ignition 8.3.9 (perspective) RV50 gateways-identically replicated radio templates except for LAN IP and local host ip ("primary" radio pointed at primary gateway, "redundant" radio pointed at backup gateway). Of course the WAN side is different too. I can see my text message response PINs in the backup cell gateway when testing, so it is getting there. Don't believe I ever setup any firewall rules on the server to get the modem working. In any case the redundant was the old, lone modem. ---
**Author:** ![jay](https://avatars.discourse-cdn.com/v4/letter/j/ed8c4c/32.png) [@jay](https://forum.inductiveautomation.com/u/jay)\ **Post date:** [September 22, 2026, 12:05am UTC](https://forum.inductiveautomation.com/t/sms-acknowledgement-on-backup-gateway/117132/2 "2026-09-22T00:05:12Z")
The RV50 probably has the IP address of the primary gateway hardcoded in its SMS configuration. ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/2/c/2cb9d42b004e774fa67b0e299087cd10266fdef1.png) The ack will always go the the primary gateway. ---
**Author:** ![bpomerhn](https://avatars.discourse-cdn.com/v4/letter/b/41988e/32.png) [@bpomerhn](https://forum.inductiveautomation.com/u/bpomerhn)\ **Post date:** [September 22, 2026, 3:28am UTC](https://forum.inductiveautomation.com/t/sms-acknowledgement-on-backup-gateway/117132/3 "2026-09-22T03:28:43Z")
Thanks for the suggestion, but I did check that and confirmed it is set for the redundant gateway. Only difference between the two (besides WAN side) is LAN IP and local host IP under the SMS service settings. ---
**Author:** ![jay](https://avatars.discourse-cdn.com/v4/letter/j/ed8c4c/32.png) [@jay](https://forum.inductiveautomation.com/u/jay)\ **Post date:** [September 22, 2026, 2:09pm UTC](https://forum.inductiveautomation.com/t/sms-acknowledgement-on-backup-gateway/117132/4 "2026-09-22T14:09:00Z")
The only other thing I can think of is you have your firewall receive port (17342) open for TCP instead of UDP. The SMS ack uses UDP.