What is fax passthrough?

What is fax passthrough?

Fax passthrough is the transportation of fax communications over an IP network using a low compression codec like G. Fax passthrough occurs using one of two methods on Cisco voice gateways, NSE-based passthrough or protocol-based pass-through.

What is t38 fax relay?

The T. 38 fax relay standard was devised in 1998 as a way to permit faxes to be transported across IP networks between existing Group 3 (G3) fax terminals. T. 4 and related fax standards were published by the ITU in 1980, before the rise of the Internet.

What is NSE Cisco?

Cisco utilizes proprietary NSEs or Named Signaling Events to handle switchovers for a variety of different transport methods, especially for FoIP. NSE messages are sent inband using an existing voice RTP stream. All NSE packets use an RTP payload type of 100 by default.

What is fax relay?

The fax relay feature facilitates replacement of the PSTN time-division multiplexing (TDM) infrastructure with VoIP. Feature Design of Cisco Fax Relay. Cisco Fax Relay is a proprietary fax relay implementation that uses Real-time Transport Protocol (RTP) to transport fax data.

What are fax protocols?

The protocol defines the transport of data (a fax) between PSTN fax terminals through a fax gateway, between two Internet-aware fax terminals, or from a PSTN fax terminal through a fax gateway to an Internet-aware fax terminal. A T. 38 stream is sometimes referred to as Fax over IP (FoIP).

What is fax protocol?

T. 38 is a protocol that describes how to send a fax over a computer data network. It is needed because fax data cannot be sent over a computer data network in the same way as voice communications. 38 is described in RFC 3362, and defines how a device should communicate the fax data.

What is G3 fax mode?

V34. V34 is a communication mode used for the Super G3 fax communication. This can shorten the communication time and reduce communication costs because a single page of letter/A4 size paper can be sent in as little as approximately three seconds. By default, this machine transmits faxes with V34.

Which is the best pass through protocol for fax?

For implementing fax passthrough with third party devices, such as voice gateways and proxies, protocol-based pass-through is the recommended solution since its uses standards-based call control protocols for the switchover. NSE-based passthrough is Cisco proprietary.

Can a fax be pass through on Cisco?

Fax pass-through is only supported on Cisco IOS voice gateways for the H.323 and SIP call control protocols. The command to enable this feature is fax protocol pass-through, which can be configured directly under the VoIP dial peer or globally under voice service voip.

How does fax pass through work with SIP?

The SIP re-INVITE message is sent by the terminating voice gateway when it detects the V.21 fax flags. Figure 2 demonstrates the call for fax pass-through with SIP as the call control protocol. Fax pass-through is only supported on Cisco IOS voice gateways for the H.323 and SIP call control protocols.

Is there a unified cm for fax passthrough?

Protocol-based fax pass-through is not supported by Unified CM. Modem passthrough uses NSEs so that the switchover happens without Unified CM involvement. Protocol-based T.38 is fully supported for H.323, SIP, and MGCP in Unified CM 6.0 (1).