Thanks for the feedback. I have plenty of experience with IVRs and Dialogic cards (starting with D121/LSI120s and SS96s under DOS in the 90's all the way up to Intel's DM/Vs) and didn't ever have a problem with DTMF collection with ISDN PRI lines except occasionally with wireless and cell phones (Bad line quality).
These new cards are so much cheaper than the Dialogic cards were, I should just buy the version with the cancellers. Tony On Tue, Mar 17, 2009 at 11:36 AM, Steve Underwood <[email protected]>wrote: > David Knell wrote: > > Steve Underwood wrote: > >>> When there is Echo being generated from the far end, usually in a > >>> bridged call. If you application is just an IVR, with no far end > >>> connectivity, then you shouldn't need an echo can. If you are bridging > >>> calls, then at some point you may need it, depending on what else is > >>> in the loop. > >>> > >> This is VERY VERY WRONG. IVRs badly need echo cancellation. Without it > >> they give very poor reliability detecting DTMF while the prompts are > >> playing. If the system uses voice recognition, its reliability will be > >> even worse. > >> > > With respect, this is at best half true. DTMF detection has always > > worked just fine > > without echo cancellation - the Dialogic, Aculab and Rhetorex cards > > which I used > > in the late 1990s managed it perfectly well; if the DTMF detection > > code in * and FS > > can't, then maybe that's something for its author to look at ;-) > Try reading the Dialogic and Aculab documentation. Those cards used > quite a bit of their DSP capability to remove the spillback of outgoing > voice into their DTMF receivers. You'll find the DTMF detector in > spandsp (not necessarily the ones in * or FS, which have been altered a > bit) is superior to either Dialogic or Aculab's. > > ASR - yes, maybe, but L&H's ASR1500 used to work perfectly well on the > > same > > hardware above back in the day. I'd be interested to see results of > > testing an ASR > > engine in with echo; unfortunately, most vendors appear to prohibit > > the publication > > of test results in their licensing. > L&H used to work fine with the J series Dialogic cards. The Dialogic > documents go into considerable details about the echo cancellation > arrangements to make that happen. > > Regards, > Steve > > > _______________________________________________ > Freeswitch-users mailing list > [email protected] > http://lists.freeswitch.org/mailman/listinfo/freeswitch-users > UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users > http://www.freeswitch.org >
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