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voip communication problem between site connected over frame relay.

eggster34 asked
Medium Priority
Last Modified: 2012-08-14
hello I have a point-to-point frame-relay environment where sites connect to a 3mbit frame relay pipe on my main site (with a 1751 router) and then this 1751 router connects to a catalyst 4604 router which provides voip functionality.

all sites can call the main site without problems EXCEPT for one of the sites. when this site calls any ip phone on the main site, the remote site can hear the main site talking, but the main site cannot hear the remote site talking.

there are also errors like this on both sites:

SP error stats
*Feb  7 14:31:43.471: %VTSP-3-DSP_TIMEOUT: DSP timeout on channel 3/0:1:1175, event 6: DSP ID=0x2: DSP error stats
*Feb  7 14:31:52.731: %VTSP-3-DSP_TIMEOUT: DSP timeout on channel 3/0:1:1220, event 6: DSP ID=0x7: DSP error stats
*Feb  7 14:32:32.671: %VTSP-3-DSP_TIMEOUT: DSP timeout on channel 3/0:1:1179, event 6: DSP ID=0x1: DSP error stats
*Feb  7 14:32:39.175: %VTSP-3-DSP_TIMEOUT: DSP timeout on channel 3/0:1:1232, event 6: DSP ID=0x7: DSP error stats
*Feb  7 14:34:39.067: %VTSP-3-DSP_TIMEOUT: DSP timeout on channel 3/0:1:1200, event 6: DSP ID=0x6: DSP error stats
*Feb  7 14:37:01.795: %VTSP-3-DSP_TIMEOUT: DSP timeout on channel 3/0:1:1258, event 6: DSP ID=0x8: DSP error stats
*Feb  7 14:37:32.683: %VTSP-3-DSP_TIMEOUT: DSP timeout on channel 3/0:1:1105, event 6: DSP ID=0x3: DSP error stats
*Feb  7 14:38:12.511: %VTSP-3-DSP_TIMEOUT: DSP timeout on channel 3/0:1:1263, event 6: DSP ID=0x8: DSP error stats
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It could be the RTP voice packets are being blocked from the remote site to the main site. Do you have any filtering or firewalling in place?
It is probably related to the first answer, but you can do a show dsp and ensure that the DSP are not being chewed up somewhere else.

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we changed the codec and fixed it.. thanks alot.
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