Voice over Internet Protocol (VoIP)

Voice over Internet Protocol (VolP) is a technology that allows you to make voice calls using a broadband internet connection instead of a regular (or analog) phone line.

VolP is also the foundation for more advanced unified communications applications such as web and video conferencing.

Early VolP implementations were proprietary, making integration and interoperability between vendors difficult. The adoption of RFC 2543 in 1999 provided an open standard for VolP systems. The Session Initiation Protocol (SIP) enables any SIP compatible device to communicate with any other SIP system.

The standard effectively opened the telecommunications markets to broad competition for voice services.

In all Voll systems, your voice is converted into packets of data and then transmitted to the recipient over the internet and decoded back into your voice at the other end. To make it quicker, these packets are compressed before transmission with certain codecs, almost like zipping a file on the fly.

There are many codecs with diverse ways of achieving compression and managing bitrates, thus, each codec has its own bandwidth requirements and provides different voice quality for VolP calls.

Different VolP implementations provided different approaches to allow users to connect calls between IP network endpoints such as smartphones and laptops with callers on analog phones connected to the public switched telephone network (PSTN).

As its name implies, Session Initiation Protocol (SIP) is designed to manage multimedia connections. SIP is designed to support digest authentication and integrity protection through MD5 hash functions. SIP also supports a variety of encryption mechanisms, including as TLS. Privacy extensions to SIP, including encryption and caller ID suppression, have been defined in extensions to the original Session Initiation Protocol (RFC 3325). Many jurisdictions, including the United States, require VolP systems to provide Enhanced 911 (E911) services, geolocation and other capabilities that are present in traditional voice telephony.

From a business use-case perspective, VolP has largely been absorbed into the whole panoply of multimedia collaboration platforms, such as Zoom, Microsoft Teams, Skype, and others. These have a wide range of form, function and capabilities.

From a security perspective, when compared to traditional voice telephone calls, VolP and multimedia collaboration platforms can offer a variety of encryption, call logging, recording, and conferencing capabilities that go far beyond what the plain old telephone system (or POTS) could ever provide.

From a security perspective, this is both good news and bad:

• The good news: Security policies can enforce meeting or call security, limit access, and protect proprietary or sensitive content. Automated recordkeeping provides a basis for audit and investigation if required.
• The bad news: Some of these products and services may involve encryption solutions, which have been compromised or cracked by various national governments or other parties.