Pulse code modulation upstream, commonly called PCM upstream, is a feature of V.92 that boosts the upstream data rate for dial-up modems to a maximum of 48 kilobits per second.
The upstream rate is the speed at which data can be sent from the user's computer to the ISP (Internet service provider). It is typically slower than the downstream rate, which is the speed at which data is sent from the ISP to the user's computer.
Introduced in 1999, V.92 is the current mainstream international standard for dial-up modems. The maximum upstream data rate for the former V.90 standard was 33.6Kbps.
This increase in the upstream data rate has substantially reduced the times required for users to send e-mails with large attachments (e.g., photographs and music) and to upload large files to web sites, and it has improved the performance of interactive applications.
Created November 11, 2005.