These services have been commercialized using the PHS Internet Access Forum Standard (PIAFS), the PHS protocol that was standardized by the PHS Internet Access Forum in March 1996. (For further information about PIAFS, see "PHS MoU News" No. 6, October 1996 issue.)

The PIAFS protocol specifies an end-to-end transmission control scheme, including error correction and retransmission control procedures. It achieves an effective transmission of 29.2 kbps. Compared with the 9.6 kbps transmission speed of cellular phones, it offers considerable advantages with respect to both transmission quality and cost. Three types of interconnections for data communications are possible:
1) between PHS terminals;
2) between PHS-PIAFS-compatible terminal adapters; and
3) transmission from a PHS terminal to an analog modem.

The PIAFS protocol supports a wide-range of services while away from the office, including e-mail and fax service, Internet access and image transmission, among others. With these broad capabilities, it is expected to meet the rapidly growing needs for mobile data communications.
Most Internet access providers use ISDN lines at their access points providing dial-up connections. However, to facilitate communications with a PIAFS-compatible terminal via an ISDN line, the access provider must install a PIAFS-compatible terminal adapter. PHS operators have encouraged Internet access providers to install terminal adapters so as to enable PHS users to download information in real-time from the World Wide Web, for which there are substantial needs. As a result, the following Internet access providers now support the use of PIAFS:
NTT PC Communications (InfoSphere), Atson (ASAHI Net), ASCII (ASCII Internet Service) Bekkoame Internet (BEKKOAME/INTERNET), NEC (BIGLOBE, C&C mesh), Mediabank (DREAM-NET), Internet Initiative (IIJ Internet Service), Fujitsu (InfoWeb), JustSystem (JustNet), Nifty (Nifty-Serve), NetworkService (NIS Internet Service), NTT Data (InterVia), Tokyo Internet (TokyoNet Internet Service)

On the terminal front, many companies have released PIAFS-compatible PHS terminals, communications adapters, PC memory cards and other products.
A manufacturer supplying equipment to the DDI Pocket Telephone Group has put on the market a terminal that integrates a PHS handset with a built-in modem and a Personal Digital Assistant (PDA). Besides voice communications, the built-in modem provides a capability for exchanging e-mail. Also, the lower part of the terminal accommodates a PCM-CIA Type II card, which can be inserted in the card slot of a notebook PC to facilitate use as a modem. Though the built-in modem provides a transmission speed of 2,400 bps. Data transmission at 29.2 kbps is possible by installing PIAFS-compatible software.