Unknown connection attempts to UDP-Port 3478 (STUN)


Some (perhaps 20) of our (not all, with different firmware) GXP2130 (100+) attempts to register on an STUN-Server @
But nowhere in the config-dump i found this server. What’s going on?


Look in the phones or PBX for a stun server like stun.ipvideotalk.com. These should not be registration attempts, but rather queries to determine the public IP of the router they sit behind.


We habe dumped the config file. No entry for a stun server. Out PBX is located in our internal lan, so we do not neerd any stun server.


Where your PBX/Phone is located is not necessarily a factor. It is a question of whether the PBX has a need to know what the public IP is so it can communicate correctly with remote phones or providers and tell them how to reach back to the PBX/phone for SIP messaging. So, it is a question of where or if any external needs and if there is a static public IP or FQDN populated in the NAT settings of the PBX/

Not knowing more of the situation, it’s all i can offer.


Saw a ton of these recently. GrandStream phones are phoning home.


Dear Grandstream users,

IP address is the STUN server used by Grandstream end devices to communicate with GDMS (Grandstream Device Management System) via TR069 and it’s enabled by default. It allows devices to maintain connection with GDMS. This server information was previously disclosed and published as known server used for GDMS connection here:

Product security is crucial to us and our customers. If you prefer not to use GDMS service, this can be disabled by unchecking option “Enable TR069” on device webUI (if supported) or removing the default configuration “https://acs,.gdms.cloud” for option “ACS URL”.

Thank you for your support and understanding as we continually work to improve our products. Please feel free to contact Grandstream support if you have any questions or need assistance.

Grandstream Support