1¡¢usb 2.0 port 2¡¢16 bit sound card inside, the pc can without sound card 3¡¢support h.323, sip, mgcp etc lot of protocol 4¡¢support product serial write in 5¡¢with hid (human interface device) feature 6¡¢plug & play to install usb driver 7¡¢no driver needed for win98 se/win me/ win 2000/win xp/ mac os/mac os x 8¡¢with pid (physical interface device) feature 9¡¢implement ¡°real-time¡± verification 10¡¢compatible with major pc¡¯s internet phone application software 11¡¢provides ringer generation for pc to pc call through existing ip phone applications 12¡¢optional itsp application software with credit for pc to phone connection 13¡¢aled to indicate power and linking status 14¡¢adjustable volume for handset 15¡¢support e.164 dialing rule danny@vnetphone.com www.vnetphone.com skype:cnwxdkj