Because VoIP sends your conversations over the internet as data, those conversations can, in principle, be intercepted if they are not protected. Encryption is the safeguard that keeps calls, voicemails, and messages private as they travel and while they are stored. For any organization handling sensitive information, understanding VoIP encryption is essential.
Two things to encrypt: signaling and media
A VoIP call has two streams that need protection:
- Signaling: The information that sets up and controls the call (who is calling whom). This is commonly protected with TLS (Transport Layer Security), the same protocol that secures websites.
- Media: The actual audio of the conversation. This is commonly protected with SRTP (Secure Real-time Transport Protocol), which encrypts the voice packets.
Protecting both is important. Encrypting the media but not the signaling, or vice versa, leaves part of the communication exposed.
Encryption in transit vs. at rest
| State | What it means | Why it matters |
|---|---|---|
| In transit | Data moving across the network during a call | Prevents eavesdropping on live calls |
| At rest | Stored data like voicemails and recordings | Protects archived sensitive content |
A truly secure setup protects communications in both states. A call may be encrypted while it travels, but if the resulting voicemail or recording sits unencrypted on a server, that stored data is still at risk.
Encryption and HIPAA
Under the HIPAA Security Rule, encryption is an addressable implementation specification, meaning organizations must assess it and implement it where reasonable and appropriate, or document why an equivalent alternative is used. In practice, encryption of PHI in transit and at rest is a widely adopted and strongly recommended safeguard. The HHS guidance on securing electronic PHI treats strong encryption as a key protection.
What to ask your provider
- Is call media encrypted (for example, with SRTP)?
- Is call signaling encrypted (for example, with TLS)?
- Are stored voicemails, recordings, and logs encrypted at rest?
- How are encryption keys managed and protected?
- Are messages and any texting features encrypted as well?
Encryption is necessary but not sufficient
Encryption protects data from interception and unauthorized reading, but it does not address every risk. Strong access controls, authentication, secure device configuration, and protection against account takeover all remain essential. Encryption is one critical layer in a defense-in-depth approach, not a complete security strategy.
Practical takeaways
- Insist on encryption for both call signaling and media.
- Confirm stored sensitive data is encrypted at rest, not just in transit.
- For regulated data, document encryption as part of your safeguards and risk analysis.
- Pair encryption with access controls and monitoring for meaningful security.
Encryption turns your VoIP traffic from readable conversations into protected data. For organizations handling sensitive or regulated information, verifying that a provider encrypts communications properly is a non-negotiable part of due diligence.