SDK 6.7.3 is the latest Brooktrout development kit providing feature-rich capabilities to our partners. As usual, we’ve added some new features that will be quite useful, and I will discuss a few of them here to give more details on what they do and why they can help you. First up is the ability to enable or disable Error Correction Mode on a per call basis.

Error Correction Mode (ECM) is a fax feature where image data is broken up into chunks called frames and each frame has a checksum applied to it. If any data is corrupted during transmit, the receiving side tells the sender about it and which frames were bad so that the sender can re-send the bad ones. Previously, the Brooktrout SDK allowed the ability to enable or disable ECM only during the channel reset, usually from the btcall.cfg file with the ecm_enable parameter.

There can be times though when you want to disable ECM for a particular call. Maybe you know a particular phone number doesn’t handle ECM well for some reason and so you’d rather not use ECM then. In SDK 6.7.3, you can now override the btcall.cfg setting when you call your first fax function (e.g. BfvFaxBeginReceive, BfvFaxBeginSendTiff). We’ve added a new parameter in the args_fax structure called ecm_override. If you leave it at 0, then whatever is set for the ecm_enable parameter in the btcall.cfg file will still be in control. If you set ecm_override to a positive value, it will override ecm_enable and enable ECM, and if you set it to a negative value, it will override ecm_enable and disable ECM.

This feature can be especially useful in conjunction with the “Support for a Changed DIS” feature added in SDK 6.7.2 where if a receiving fax device changes certain DIS parameters, the Brooktrout board will no longer hang up the call with an error 33. If the changed DIS changes one of the more “important parameters” (width, resolution, line compression, ECM), then the change must be something that would not affect the settings the Brooktrout side was planning to use. To put it another way, if the remote end sends a changed DIS that disables ECM (when at the beginning of the call, the first DIS had ECM enabled), there would be no issue as long as the Brooktrout side already had ECM disabled as well.

So with the new feature, an application could disable ECM only to this particular number that it recognizes as disabling ECM so that the call can go through. You can think of this as sort of an ECM blacklist.

Here’s a piece of a Brooktrout debug log to show you ecm_override in action. The first section is from during a channel reset. (Resets have a lot of information so I’m showing only a piece of it.)


06/19 16:41:25.08 56[41,2] >+ (09) FAX (0A) REQUEST (7F) GET_CAPABILITIES

06/19 16:41:25.08 56[41,2] < (09) FAX (08) EVENT (7E) CAPABILITIES_LIST

(37) CAP_FORMATS [02: Fix Uns Long Unitless] 0000000F

(38) CAP_FEATURES [02: Fix Uns Long Unitless] 005FF6B7

06/19 16:41:25.08 56[41,2] > (09) FAX (04) SET

(2E) ECM_ENABLE [00: Fix Uns Byte Unitless] 01

(2F) ERROR_ENABLE [20: Fix Uns Byte Boolean] 01

(30) ERROR_MULT [00: Fix Uns Byte Unitless] 28

(55) RTP_MULT [00: Fix Uns Byte Unitless] C8

(31) ERROR_THRESH [00: Fix Uns Byte Unitless] 03

The line above with “ECM_ENABLE” in it has a 01 at the end to indicate the ECM is enabled here from the btcall.cfg file. Then later in the log after the SR140 has answered the call, the BfvFaxBeginReceive API function is called with ecm_override set to -1. The code would look something like this:

printf( “BfvFaxBeginReceive\n” );

BT_ZERO(args_fax); args_fax.ecm_override = -1;       // override ecm_enable in btcall.cfg and disable ECM

if (BfvFaxBeginReceive(lp, &args_fax) < 0)


Error handling code here



This causes there to be another “ECM_ENABLE” line in the debug log, but this time the line has a 00 in it. The 00 indicates that ECM is now disabled regardless of the ecm_enable setting in the btcall.cfg file.



06/19 16:41:29.31 56[41,2] rcv startup

06/19 16:41:29.31 56[41,2] > (09) FAX (04) SET

(2E) ECM_ENABLE [00: Fix Uns Byte Unitless] 00

06/19 16:41:29.31 56[41,2] > (09) FAX (04) SET

(4D) V34_ENABLE [20: Fix Uns Byte Boolean] 00


499 Blog Image

Just as early pioneers of the western frontier forged through uncertain peril in uncharted lands to discover new territories, the fifth generation (5G) mobile communication network architecture and supportive facilities will introduce new technologies, business models and services that will change the modern day way of life. Network Functions Virtualization (NFV) and Software Defined Networking (SDN) will play vital roles in facilitating the Communication Service Provider’s (CSP) transition from legacy 2G, 3G and 4G mobile network technologies to 5G because of the innate and fundamental benefits they offer compared to the classical architectural approaches of the past.

These benefits include:

  • Strategic reduction in CAPEX , OPEX
  • Network service agility (i.e. faster time-to-market and monetization of new services)
  • Tactical dynamic scalability, high availability, and redundancy

These are a confirmation of the conjugal relationship between the two technologies and how actualization of the next mobile frontier will depend on NFV and SDN and other supporting 5G technologies.

5G requires re-thinking from previous mobile network technologies

To provide an infrastructure for the new services and applications envisioned for 5G, it is generally understood by leading technologists that the existing mobile network infrastructure will have to drastically change. 5G will require a “rethinking” of the existing infrastructure networks and possibly need a complete overhaul. The traditional migration model used when transitioning from 2nd , 3rd and 4th generation mobile technology is not sustainable for the new business models foreseen in 5G. These new models will ultimately result in major upturn in device capacity, traffic volume and response time demands.

499 Blog Image 2

Source: 4G Americas’ Recommendations on 5G Requirements and Solutions


The criteria envisioned for 5G as outlined in GSMA’s “Understanding 5G: Perspectives on future technological advances in mobile” are substantial:

  • 1000 x more connected devices
  • 30 x higher smart-phone density (up to 12,000 devices per km^2)
  • 1ms or less RTT latency
  • 100 x higher average data rate
  • 10000 x mobile data volume

These requirements will require an infrastructure that is highly flexible, dense, fast, accessible, resource efficient and can scale as needed to meet the dynamic needs of the underlying network services. In the next installment of this 4-part blog we’ll outline some of the 5G objectives and challenges that need to be overcome to get there. Let us know what you think about 5G and the implications of the technology. You can tweet us at @Dialogic.


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