From Forum Nokia Wiki

System property com.nokia.network.access has been available also in S60 devices since S60 3rd edition FP2. The possible return values are: • pd - Packet data in GSM network • pd.EDGE - Packet data in EDGE network • pd.3G - Packet data in 3G network • pd.HSDPA - High speed downlink packet access for 3G networks • csd - Circuit switched data, for example GSM CSD/HSCSD data call • bt_pan - Bluetooth PAN network • wlan - Wireless network, for example 802.11b, 802.11G or WiMaX • ‘na’ Not applicable, the implementation can’t determine the type