Fax classes denote the way fax programs interact with fax hardware. Invoices can be sent via email, postal mail, fax, or EDI. Radio and satellite systems can include navigation, telephone, fax, and email capabilities. Many of these transfer scams involve a notice sent in the mail, fax, or e-mail. Police traced the fax to Albrett using the phone number listed in the fax header. This includes office equipment such as printer, fax machine, computers, refrigerator, etc. Users could message advertisers and have that message forwarded to their fax machine. No software, fax server or fax machine is needed. There are also secure and non-secure voice, fax and data communications facilities. Services using SIP-I include voice, video telephony, fax and data. Assume we have received a fax of a dark photocopy. DID service is also used by fax servers. Related exploits include SMS flooding attacks and black fax or fax loop transmission. Equipment such as hardware routers, switches, blank CDs, and fax machines were also seized. Thus, some way of transmitting fax over IP was needed.