The INI SipPhone is an application for making and receiving calls to and from other phones, either IP-based or landlines/cellphones (via a gateway). The system was designed for the SHARP SL-5500 Zaurus PDA, but may work on Linux desktops or laptops as well. It should also work with other Linux PDAs like the YOPY made by Samsung or the iPAQ made by COMPAQ.
The AerLink NPC(http://www.sdgsystems.com/) is a high-speed data connection cable that connects the Zaurus to a cellular handset. The AerLink NPC goes well beyond the distance limitations of BlueTooth and 802.11 networks, providing access to e-mail and the Internet in most areas where you can make a cellular call. The AerLink NPC supports many popular cellular handsets along with high-speed cellular data technologies, such as 1xRTT and GPRS. Before the AerLink NPC, wide area connections were often limited to using slower technologies, such as CDPD, or using an inconvenient infrared connection to a cellular handset. The AerLink NPC utilizes the Zaurus' CompactFlash slot and communicates to the cellular handset using a high-speed serial connection. Data rates range from 9.6Kbps, using older data technologies, to 144Kbps bursts, using high-speed data technologies.
Other CF cards see in the Linux PCMCIA/CF-Card Survey.
For GRPS see the GPRS-HOWTO(http://turtiainen.dna.fi/GPRS-HOWTO).
See the Linux InfraRed-HOWTO .
See this survey.