Which type of inside wire is most commonly used today for telephone and data circuits?

The most commonly used type of inside wire today for telephone and data circuits is Cat 5e. This category of cable enhances the performance of the earlier Cat 5 standard by reducing crosstalk and allowing for higher data rates. Cat 5e is capable of supporting data transmission rates of up to 1 Gbps over distances of up to 100 meters, making it suitable for a variety of applications, including broadband Internet connectivity, VoIP, and standard telephone services.

While Cat 6 and Cat 6a cables provide increased performance and bandwidth over Cat 5e, their usage is typically more prevalent in environments requiring higher data rates, such as enterprise networks or for future-proofing with applications expecting higher demands. Cat 7, while offering even higher performance specifications, is not commonly implemented in residential settings due to its higher cost and installation complexity.

Given that Cat 5e strikes a balance between cost, performance, and ease of installation, it remains the go-to choice for most residential and small commercial applications, positioning it as the most widely deployed cabling solution for telephone and data circuits.