Today, it is possible that you can use even fax machines over IP. This innovative technology is quite difficult to use. For proper and successful operation of the same, your fax requires certain things.
Listed below are the fax requirements:
1. Signal – Analogue telephone
2. Necessary bandwidth for data transmission
3. There should be no broken signals, other hindrances etc
Next, coming to the problems related to faxing over IP, they are as follows:
1. The signal carried by VoIP is digital and not the one required by fax, which is analogue signal.
2. Required bandwidth for data transmission is not provided to fax by VoIP.
3. When using VoIP, there are chances of data loss while transmission. We humans might not feel the slight difference when a small packet sized data is lost. However, fax machines, as very sensitive, during such data loss, they might stop the transmission.
As a result of the above problems, using fax over IP is complicated. The rate of success of using the same is 70%, even when used with best available connections. However, leaving apart these difficulties, let us see how you can make a better use of the same. For better understanding, Linksys adapter’s settings are used.
The steps are listed below:
1. G711u, as they have the required bandwidth for faxing, you should set your codec to the same.
2. You should set your RTP packet size to 0.020 or 0.010. This is a time measurement value in minutes that each data packet contains. As data loss takes place, its better you lose less data, so that high error recovery is possible for your fax.
3. Until you get done your fax transmission, its good if you stop all interruptions like uploads and downloads and even videos, with the 15/5 Mbit connection that you have, and of course which is the latest.
4. ECM is not that good for error correction on IPs, as they are on POTS. Hence it is better that you disable the same on your fax.
5. As a result of limited bandwidth, it is better that you reduce the data transfer speed, by using the overseas mode available in certain faxes. While some faxes come with an option to reduce the speed. To face the problem of less bandwidth, you should either use the minimum speed, that too below 9600bps or never use bandwidth.
6. In between your Analogue telephone adaptor and fax, place a DSL filter.
7. Errors depend on the number of pages on your fax session. Hence, it is better to fax a maximum of 2 to 3 pages, so as to reduce errors. Now, this means that, it is best to avoid documents of multi page.
8. Fax is more conscious about acquiring accurate signals, and not much concerned about echo. Hence, you should disable the option of echo cancellation available on your Analogue telephone adaptor. It is advisable that you enable the same on Line 1 and on Line 2, disable it.
9. Silence suppression, when opted, it saves a lot of bandwidth. However, it is good to disable this option of silence suppression on your fax, to save the very low bandwidth that you have. Clarity of signals as well as quality of voice would have to be sacrificed by you, and it is sure that it will not be approved by your fax.
10. Your Codec Symmetric should be set to number.
11. Your passthrough method has to set to ReINVITE.
12. Both your FXS Port input gain and FXS Port output gain has to be set to -3, which is Linksys adapters default value.
These are some of the steps, when followed, increases the success rate of faxing over VoIP. However, the rate of success will only be a little higher than that what you get normally. If your business mainly depends on faxes and you do more of them, then its better you place a landline and you might have read in most of the articles that, at least one landline is a must have for making proper 911 available.
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