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Commetrex has developed fax technologies serving the telecom-equipment developer for over a
decade, resulting in a rich library of major system components: PortableT30™ (P30) and the Fax
Modem Bundle provide PSTN fax termination. PowerRelay™ for T.38 implements the ITU
recommendation for real-time IP fax. And TerminatingT38™ combines P30 and PowerRelay to
support real-time terminating fax on IP media servers. Multi-Modal Terminating Fax (MMTF) is an
integration of all of these major system components to create a system that allows a media server to
terminate faxes from PSTN-IP gateways supporting either T.38 or G.711 pass-through for fax
transmissions. Several versions are available for Commetrex’ BladeWare host-signal-processing
system and for the Texas Instruments TMS320C6000 DSP in XDAIS format.
- Commetrex T.38 Interop Lab certified
- Commetrex’ exclusive TerminatingT38
- Commetrex’ PortableT30
- Image Conversion Library
- Fax modems: V.21, V.27ter, V.29, V.17
- Fully embedded TI ‘C6000 XDAIS version
- BladeWare ready
- Field proven
- Fully documented
- Send and receive faxes from a server to any gateway or Internet-ready fax terminal
- Minimum time to market
- High customer satisfaction
- Easy to integrate
- Highest interoperability
- Per-port runtime with BladeWare
- Limited-use paid-up source code
- Corporate paid-up source code
- Source with runtime license
- Paid-up object code
- Object code with runtime license
With the growing movement towards IP
telephony and the release of T.38, the
specification for real-time fax over IP,
Commetrex developed TerminatingT38. The
Company’s field-proven PortableT30 protocol
engine was integrated with its T.38 PowerRelay
protocol engine in a manner analogous to the
way T.30 uses analog modems to process the
call stream. (See illustration below.)
This permits the termination of T.38 streams in an IP
network on a host computer without the need
for modems. TerminatingT38 requires
comparatively few MIPS since there is no need
for signal processing. (See illustration below.)
As a result, TerminatingT38 is suitable for any
processing environment that supports the
memory requirements and an IP stack.
But, in order to provide fax termination to any
IP connection, T.38 alone is not sufficient since
not all IP gateways support T.38. Therefore, a
system that can terminate a fax session over
any IP connection must support both T.38 and
packetized G.711, sometimes called G.711
pass-through. (See illustration, preceding
page.)
Typically, PortableT30 operates on a host
computer or scalar/co-processor, while the fax
modems operate on a DSP resource. This
partitioning is dictated by the light processing
and relatively heavy memory requirements of
the T.30 stack and its need to process the TIFF-
F file format, and the efficiency of a DSP in
processing the sampled data of the analog call
stream.
The core of MMTF is Commetrex’ PortableT30
(P30) finite state machine (FSM). This
component contains the T.30 stack, image
handling, and ECM (error correcting mode)
support. P30 interfaces with either the modem
hardware adaptation layer or the T.38
adaptation layer (HAL or the T.38 HAL). Both
of these packages present the same interface to
the P30 FSM. The P30 FSM sends commands
and data to these packages. Internally, each of
these packages processes the commands and
data to generate output, either as G.711 modem
data or T.38 packets. Alternatively, these
packages decode external fax data, either as
G.711 or as T.38 packets, into data and events.
These decoded events are used to trigger the
operations of the P30 FSM.
MMTF is available in two versions: BladeWare
and XDAIS. BladeWare is Commetrex’ host
signal processing software framework; XDAIS
is a fully embedded version available in the
Texas Instruments TMS320C6000 XDAIS
format.
For the last few years, the MIPS available on
Pentium-class PCs have been adequate to
process over 100 media streams while still
leaving ample processing power to host several
applications. The capacity doubles every 18
months according to Moore’s Law. Blade
servers make scaling the number of open-
architecture processors in a system as easy as
adding a DSP-resource board, and the densities
are nearly the same. But, although blade-server
architecture makes scaling the number of
processors a snap, the software required to
harness those MIPS and provide seamless
system scaling through the addition of
processors has not been available. BladeWare
from Commetrex, featuring Open
Telecommunications Framework® Kernel and
OpenMedia™, solves the problem.
BladeWare is available as a comprehensive
software developer’s kit, which supports
development of servers that support both voice
and fax. BladeWare’s call routing and dynamic
resource allocation mean that the application
software need not be aware of whether a fax
transaction is made over T.38 or G.711 pass-
through using host signal processing-based fax
modems.
In the embedded version of MMTF, the OEM
framework/application controls MMTF via the
XDAIS “algorithm” interface. It periodically
calls MMTF via the apply() function to
process/generate T.38 or G.711 packets. The
OEM application must call this function every
processing period to permit the MMTF to
generate outputs and run its timers.
For G.711 mode, the OEM application must
supply jitter buffering on the RTP stream. For
T.38 mode, MMTF handles the jitter buffering
since RTP is not used with T.38.
The memory and processing requirements for
the embedded version of MMTF are based on
the negotiated options, compilation options and
the files involved. The following table
summarizes these features of the product.
| |
MCPS (TMS320C6000) |
Per-Channel Memory |
|
| Options |
G711 Mode |
T.38 |
On-chip |
Off-chip |
Code+Tables |
| ECM Disabled |
7.9 |
3.45 |
2072 bytes |
48Kbytes |
350Kbytes |
| ECM Enabled |
8.9 |
4.45 |
2072 bytes |
118Kbytes |
350Kbytes |
Open Telecommunications Framework, PowerFax, and Commetrex are registered trademarks of Commetrex Corp. All other
trademarks are the property of their respective holders. |
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