Keep up to date with our free newsletter! Enter your e-mail to sign up. New utility downloads free utility updates, utility news, tips, new utility releases, and more... Subscribe Unsubscribe Powered by YourMailinglistProvider.com

Main Support Board Purchase Modems Connection Window Application Interface Configure Sound About Crypto Answering Authenticator Accounts Account Editor Weblinks Dialing Rules Event Logging Wans and Lans Firewalls Back Sending Device Report Change Log   Email Address:   Contact

Frequently Asked Questions About Modems   1. How do I know if my existing modem can be used with this software?   2. I use my modem as an answering machine, why isn't it detected?   3. What information is collected about the modem?   4. What information is sent to Twilight Utilities when I "Send device info to Twilight"?   5. I can make a call but the sound is just awful.   6. I can make a call but there is a terrible echo.   7. What is comfort sound?   Answers   1. Just because the application reports your modem is not supported during the detection phase does not mean your modem can not work with the product. It could also mean we do not have enough information about the modem to know if it can be supported. During detection, the software collects information about your modem. This information is used to generate lookup keys for our modem database and if there is a  'hit'  the modem is detected. However, we only add a modem to the database when we are confident we can support it.   To help with this we wrote a set of experiments you can try. If you think you modem is truly full-duplex audio, follow the posts on our support message board here to know for sure. If you have satisfied all the tests and are sure the modem should work, use the Send Device Info to Twilight button and mention your test results in the notes section of the report generator.   2. Just because your modem operates as an answering machine (TAM) doesn't mean it's VOIP ready. All a TAM demonstrates is half-duplex voice streaming where as VOIP requires full-duplex streaming. However, your modem may also operate with full duplex streaming so follow the tests on support blog about modems and let us know.   3. As part of the modem identification process, The application sends some "at" commands to the modem as well as tries to guess its TAPI registry location. The final step is to look up against our accumulated knowledge about voice modems to compare with what the modem returned. Unfortunately, there is no well adhered standard which means modems made by 2 different OEMs but the using same driver and chip sets can give 2 different answer making detection sometimes difficult.   4. As well as collecting the above mentioned data, we include the PC's windows version and attach a copy of the modem's inf file. Absolutely no personal data is collected.   5. When you have everything working and make a call and the sound is very poor, the most frequent culprit is the modem's audio levels are too high or too low. You can remedy this by watching the software during a connection and adjusting the audio sliders. The application will remember the setting from one call to the next so you fix it and forget it. Another possibility is the input channel volume of the sound card is set too high. In the case of the modem operating as a speakerphone, you must also configure the sound card's audio volumes. The audio channels you selected for the modem's sound card mixer as the active mixer sources during a call are dynamically swapped out at the start of a call and are restored after each call is completed. You only have to do this once so it's fire and forget. We call this tuning the audio line.   6. Echo during a call is frequently the result of the modem's device driver improperly subtracting comfort sound. Most digital speakerphone modems should work well for VOIP because they apply advanced AEC in order to be able to operate in open mic environments.   7. Comfort sound is a trick used for telephones so that when you make a call you do not get dizzy or disorientated. Humans have evolved with two ears and stereo hearing, when you cover one ear (say with a phone) it distorts your perceptions of the incoming sound. You hear your own voice in the unblocked ear but the other ear being covered (with the phone) will lead to difficulty in understanding the sound. You can verify this by covering one ear with a hand and talking. To overcome this, when you talk into a phone, as the sound travels to the phone company switch box the telco actually reflects a portion of the sound backwards down the wire. Because this happens faster than you can notice this, the result is that as soon as you speak you can hear your own voice in both ears, even the one you carefully covered with the phone handset. So the end effect is that you hear your own voice in both ears even though one is covered. This makes modems slightly more complex than simple sound cards because sound cards do not artificially re-inject the mic stream for comfort. If this comfort sound is delayed, say by digitizing it and routing it over the internet it is heard as an echo. Effective subtraction of the comfort sound can only occur in the modem's device driver since by the time any application begins to process the sound too much random time has passed between packets. This is why digital speakerphone modems tend to work better. Because they have to operate in an environment where, besides the comfort sound echo they are also exposed to additional artificial echoes created by speakers feeding back into the mic and so have developed robust AEC (Adaptive Echo Cancellation) This also explains why using modems for data transfer they have higher download rates than upload rates (typically 56k down and 33k up). Even in data mode modems must deal with comfort sound. A modem uploading is like you talking and since they don't want to corrupt the data stream they are a little slower and more careful when they  'talk'  so they can distinguish between what they are  'saying' , what the other party is  'saying'  and what the telco is injecting back in for comfort.