T.38 FAX Standard (relay only) |
9600 bps |
This capability is standards-based and uses IP trunks, H.323 or SIP for communicating with non-Avaya systems. Additionally, the T.38 FAX capability uses the User Datagram Protocol (UDP). For more information, see T.38 fax standard mode.
Note:
FAX endpoints served by two different Avaya servers can also send T.38 faxes to each other if both systems are enabled for T.38 FAX. In this case, the servers also use IP trunks.
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FAX Relay |
9600 bps |
Because the data packets for faxes in relay mode are sent almost exclusively in one direction, from the sending endpoint to the receiving endpoint, bandwidth use is reduced.
Note:
Do not use this proprietary relay protocol. Instead, use T.38 FAX standard or T.38 with fallback to G.711 Pass-through.
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FAX Pass-through |
V.34 (33.6 kbps) |
The transport speed is up to the equivalent of circuit-switched calls and supports G3 and Super G3 FAX rates.
Note:
You can achieve the V.34 speed of 33.6 Kbps if the IP transport network has minimum delay and only a few hops.
If you are using Super G3 FAX machines as well as modems, do not assign these FAX machines to a network region with an IP Codec set that is modem-enabled as well as FAX-enabled. If its Codec set is enabled for both modem and FAX signaling, a Super G3 FAX machine incorrectly tries to use the modem transmission instead of the FAX transmission. Therefore, assign modem endpoints to a network region that uses a modem-enabled IP Codec set and assign the Super G3 FAX machines to a network region that uses a FAX-enabled IP Codec set. You can assign packet redundancy in both Pass-through and Relay modes, which means that the gateways use packet redundancy to improve packet delivery and robustness of FAX transport over the network. The Pass-through mode uses more network bandwidth than the Relay mode. Redundancy increases bandwidth usage even more. |
T.38 with fallback to G.711 Pass-through |
9600 bps |
Communication Manager uses the T.38 protocol for fax transmission only if the protocol can be successfully negotiated with the peer SIP entity. Otherwise, Communication Manager falls back to G.711 for fax transmission. This mode requires a G.711 codec to be administered on the IP Media Parameters screen.
Note:
The T.38 with fallback to G.711 Pass-through feature only works over SIP trunks.
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TTY Relay |
16 kbps |
This transport of TTY supports US English TTY (Baudot 45.45) and UK English TTY (Baudot 50). TTY uses RFC 2833 or RFC 2198 style packets to transport TTY characters. Depending on the presence of TTY characters on a call, the transmission toggles between voice mode and TTY mode. The system uses up to 16 Kbps of bandwidth, including packet redundancy, when sending TTY characters and normal bandwidth of the audio codec for the voice mode. |
TTY Pass-through |
87-110 kbps |
In the Pass-through mode, you can also assign packet redundancy, which means that the gateways send duplicated TTY packets to ensure and improve quality over the network. The pass-through mode uses more network bandwidth than the relay mode. Pass-through TTY uses 87-110 kbps, depending on the packet size, whereas TTY relay uses, at most, the bandwidth of the configured audio codec. Redundancy increases bandwidth usage even more. |
Modem Relay |
V.32 (9600 bps) |
The maximum transmission rate can vary with the version of firmware. The packet size for modem relay is determined by the packet size of the codec selected but is always at least 30 ms. Also, each level of packet redundancy, if selected, increases the linear bandwidth usage . The first level of redundancy doubles the bandwidth usage, the second level of redundancy triples the bandwidth usage, and so on.
Note:
Modem over IP in relay mode is currently available only for use by specific secure analog telephones that meet the Future Narrowband Digital Terminal (FNBDT) standard. Do not use this proprietary relay protocol. Instead, use the V.150.1 standard-based relay protocol.
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Modem Pass-through |
V.34 (33.6 kbps) and V.90/V.92 (43.4 kbps) |
Transport speed depends on the negotiated rate of the modem endpoints. Though the servers and gateways support modem signaling at v.34 (33.6 kbps) or v.90 and v.92 (43.4 kbps), the modem endpoints can automatically reduce transmission speed to ensure maximum quality of signals. V.90 and V.92 are speeds typically supported by modem endpoints only when directly connected to a service provider Internet service. You can also assign packet redundancy in pass-through mode, which means that the gateways send duplicated modem packets to improve packet delivery and robustness of FAX transport over the network. Pass-through mode uses more network bandwidth than relay mode. Redundancy increases bandwidth usage even more. The maximum packet size for modem pass-through is 20 ms. |
Clear-Channel |
64 kbps (unrestricted) |
The Clear-Channel mode supports only clear channel data, but not analog data transmission functionality such as FAX, modem, TTY, or DTMF signals. The Clear-Channel mode is purely a clear channel data. In addition, support is unavailable for echo cancellation, silence suppression, or conferencing. H.320 video over IP using clear channel is supported if the port networks or the gateways have a reliable synchronization source and transport for framing integrity. |
V.150.1 Standard Modem Relay |
Need information |
V.150.1 protocol is standards-based and uses SIP signaling for communication with non-Avaya systems. This protocol uses one RTP port for sending RFC 2833 tone events, a second RTP port for exchanging State Signaling Events (SSE), and a third RTP port for sending the Simple Packet Relay Transport (SPRT) data packets. The sending and receiving systems negotiate for the support of V.150.1 in the SDP message set of the SIP protocol. The two principle applications are:
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