Here is a list of 820 Series part numbers.
S820BHK2-12103XG Cisco 820 Ser IOS IP/IPX/FW PLUS IPSEC 3DES
S820CHK2-12103XG Cisco 820 Ser IOS IP/FW PLUS IPSEC 3DES
S820CHL-12103XG Cisco 820 Ser IOS IP/FW PLUS IPSEC 56
S820CHVK2-12103XG Cisco 820 Ser IOS IP/FW/VOICE PLUS IPSEC 3DES
S820CHVL-12103XG Cisco 820 Ser IOS IP/FW/VOICE PLUS IPSEC 56