Re: [Serusers] Re: Echo Cancellation

Ravi, I would suggest the use of a good echo cancelling platform too. Look at your echo cancellers characteristics. The important things to look for are compliance to the G.168 standards and a good echo tail - 128ms is good or sometimes quoted in taps - 1024 taps is good. International calls have a longer delay for the voice to echo back - this delay is what the taps/echo tail have to work with. Some cheaper echo cancellers have very short tails - 16ms, which may be sufficient to handle echo on national networks, not on international network connections. Cellular networks can also have longer delays. For example Digium PRI hardware (there is a new card coming out soon that is better) has a short echo tail, where as Sangoma PRI cards have a long (128ms) tail. Quintum gateways also have echo cancellers with 128ms tails. Choose your hardware for connectivity to the PSTN carefully - it can have dramatic effects on voice quality. Neill....;o) Evan Borgström <evan.borgstrom(a)ca.mci.com> wrote: Just because you're sending both calls through the same gateway doesn't mean that your providers upstream gateways don't change depending on the destination. Your provider could have tens or hundreds of different vendors depending on where they terminate calls. Check the ECAN (echo cancellation), VAD (variable audio detection), etc settings on your ATA or IP phone. Play with the gains (turing down the tx gain on the microphone can help). Try changing codecs. Buy a book on how PSTN audio works or speech codecs, do some google searches, there's LOTS of info out there. -Evan ravi reddy wrote: _______________________________________________ Serusers mailing list Serusers(a)lists.iptel.org http://lists.iptel.org/mailman/listinfo/serusers