# Advanced Networking + Security ### Advanced Networking If your users will be using a firewall that blocks traffic except from whitelisted IP’s/ports, please contact us at to obtain a copy of our IP address list.
### Security For more information, please see [![](https://zello.com/favicon-16x16.png)Zello | Technical and Organizational Security Measures](https://zello.com/legal/security-measures/) Voice and rich media data transits the public internet encrypted by 256 bit AES, passing from sender device to receiver device through Zello servers. Under no circumstances do we store this data, EXCEPT: * When [Message Vault](https://paidsupport.zello.com/hc/en-us/articles/26951971742349-Zello-Work-Message-Vault) is enabled by the customer, in which case encrypted data will be saved—along with the original client key—for up to 2 years * When a voice message is a direct 1:1 communication and the recipient is offline, in which case the encrypted data will be stored for redelivery for up to 7 days. Once redelivered, the data is deleted Voice and rich media data will be stored on the recipient device UNLESS: * It is prevented by [configuration](https://paidsupport.zello.com/hc/en-us/articles/26992305281677-Can-I-control-history-from-the-management-console) * It is automatically deleted by policy (expiration time) * It is manually deleted by the user Voice and rich media data on a recipient device is encrypted at the operating system level on iOS and suitably configured versions of Android 7+ Additionally, we use: * 1024 bit RSA for authentication, digital signatures and secure media session keys exchange * TLS for control traffic encryption between Zello client and Zello server * All API communication occurs over HTTP/S IBM Cloud erases data using a DOD 5220.22-M grade algorithm. This ensures that any residual drive data is destroyed. This process is monitored, logged and tracked. Once complete the drive is ready to be redeployed to a new customer. If a drive fails the wipe process or reaches end of life, it is taken out of commission and physically destroyed. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://sdk.zello.com/core-concepts/advanced-networking-+-security.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.