Introduction
In the first five months of the year we have decided to check all solutions for MFC/R2 signaling at V.Office. Below is our findings.
Background information
R2 signaling is in use at several countries, including most counties from Latin American, China and Africa. Considering China and Latin America would be enough to justify the development of the MFC/R2 driver for Digium cards. Despite being a popular signaling scheme it is not supported by Digium. I haven’t seen any initiative from Digium to support R2 in the near future. Steve Underwood (http://www.soft-switch.org/) has done a wonderful job creating UNICALL that is working using Digium cards. In other hand, Digivoice http://www.digivoice.com.br/ and Khomp http://www.khomp.com.br/ developed proprietary solutions (Interface Cards) for R2 signaling. We will cover them in this roundup.
Methodology
The first thing we have done is to change the signaling of our office from ISDN to R2 (Ugghhh). It is for a good cause. We have been working with EuroISDN for two years without any problems. GVT our Telco provider can deliver ISDN and MFC/R2. We are lucky to live in south of Brasil were Telcos invested hard in the last decades. Our friends from the Sountheast, Northeast and North of the country probably won’t have the same luck. The fact is that almost 90% of the digital lines in Brazil are being signaled with R2 and ISDN is only available in state capitals and major cities. For the rest, R2 is the only option for digital signaling. We have tried eacho solution for at least two weeks. Digivoice stayed for a month in our lab bench.
Results
Digium e100P
The first card tested was Digium with the Unicall driver. We have used an E100P (old card from Digium) using Unicall during two weeks, It worked fine, without major hassles. Our volume is not huge (40 extensions) and we had zero problems working with R2. Some customers didn’t have the same luck. We had major problems with FAX over MFC/R2 in one of them. Dropped calls are being reported too to our technical support. It is very hard to troubleshoot problems, and without a manufacturer to assist, it looks like a terror movie. I would like to blame Steve Underwood (the creator), but the software is free and if he does not want to support it, I can’t blame him, he does not make any money from it and we only can try R2 on Digium cards because of him. (In Brazil we have a dictate, “You don’t look the teeth of a horse given for free”, or something like this).
Digivoice VB3030
In Brazil, Digivoice launched a card that is supposed to solve the problem. After two weeks running Digium/Unicall, let’s move to Digivoice. After a few glitches we got to install. Now, we have a manufacturer and everything will go right! Unfortunately, wrong, we still have problems with echo and these problems don’t get solved. Buggy drivers are common and the time taken with troubleshooting is far from acceptable. Fax is working and the only major problem now is echo in the PSTN. Digivoice can be used in any situation that echo is not an issue, such as an Asterisk server behind a PBX with echo cancellation, or in front of a PBX only routing calls. In these two situations the echo cancellation is done by the PBX. We have heard about some success cases in São Paulo, probably with different echo amplitudes. If you need to extend echo cancellation to values over 128 taps, you will have to reduce the number of channels processed, an unaccepted condition for us. Anyway, it is a solution that is being used in several customers in Brazil. They deserve credit to be the first solution to the problem in Brazil. If they could solve the echo problem, it would be a nice solution. After a month hearing echo is time to change.
Khomp K2E1600E
After six months with the Khomp card in house, we have finally installed it. The sound clarity of Khomp impresses. Their echo cancellation daughter card is working just fine and the driver has several utilities to help MFC/R2 configuration. Overall, the board seems to have very good hardware engineering, unfortunately it costs almost twice the price of a Digium or Digivoice card. The software drivers are still buggy and we have had major problems and failures with the driver. After some updates, they are working for a few days without problems. We will have to wait at least one month to say it is stable.
Some thoughts about MFC/R2
I believe it is time to several PBX manufacturers in our region to open and fund a MFC/R2 project for Asterisk. I believe Digium could sell more cards in Latin America and China if it supported MFC/R2 (should participate in the fund). Digivoice is not far from dominating the Asterisk card market in Latin America, it is just a question of a damn echo, but after almost a year from the launching, I’m loosing my faith.
List of countries using MFC/R2 to signal E1 lines
Argentina | India |
Bahrain | Indonesia |
Bolivia | Korea |
Brazil | Malaysia |
Chile | Mexico |
China | Panama |
Colombia landlines | Philipinnes |
Colombia cellular | Singapore |
Czech | Peru |
Honduras | Nigeria |
Malta | Gabon |
Sierra Leoa |
Conclusions
There is no winner for this comparison. All solutions for MFC/R2 present problems still unsolved. The Digium solution with Unicall driver does not have support, it is hard to troubleshoot and sometimes does not work with FAX. Digivoice is a good card, the driver is working, fax is working, but the echo problem is still unsolved. It can be tried in situations were you don’t expect to hear echo such as behind a PBX. Khomp deserves an honored mention, the clarity of the voice is really good, but the driver needs to improve a lot before being considered a released product. The size of the board (the new one is smaller) and the driver installation tied to a kernel version will delay the widespread use of this card.
The problem with R2 is very close to being solved, but I will ask for my Telco, "please give me back my ISDN !" MFC/R2 is still a nightmare. For the future, nor ISDN, nor R2, I believe SIP trunking will be the best alternative. It is time to try new things !.
