FXO inbound and outbound calls in CME 4.1(0)

Unanswered Question
Mar 28th, 2007

I have a 2821 router with a VIC2-4FXO for incoming/outgoing calls to the mobile telephone network (numbers the kind of 6........) calling through Nokia Premicell lines, and a PRI for landline calls (915983270 is the main PRI number).

Incoming calls are immediately answered by the router, and the caller hears a white background noise mixed with a new ring tone until ephone with configured dn 22 answers.

When the user with dn 22 answers, his voice is mixed with the noise and somewhat muffled.

No problem with outgoing calls.

The relevant configuration is:


voice translation-rule 1

rule 1 // /915983270/


voice translation-profile default

translate called 1


voice-port 0/0/0:15

cptone ES


voice-port 0/2/0

translation-profile incoming default

compand-type a-law

cptone ES

impedance complex2

caller-id enable


dial-peer voice 1002 pots

destination-pattern 6........

incoming called-number 915983270


port 0/2/0

prefix 6

no register e164


ephone-dn 22 dual-line

number 915983270

pickup-group 0

night-service bell


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Overall Rating: 4 (1 ratings)
sanmi Wed, 03/28/2007 - 04:21


The default for E1 is a-law.

I am more intrigued about the second ring tone that can be heared until dn 22 catches the call.

Paolo Bevilacqua Wed, 03/28/2007 - 04:32

Not sure there is a default. heck "show voice port" with and without the command to see.

Anyway, regarding the FXO port, I think you mean user gets a dialtone ? How is the call going to ephone 22? There is no connection-plar so they must dial digits, it is normal that they hear ringback while the phone is ringing.

The impedence setting on FXO may be wrong. Why don't you try an impedance sweep as recommended:


Hope this helps, if so please rate posts!

sanmi Wed, 03/28/2007 - 07:00

Confirmed, compand-type a-law does not produce any changes in the running configuration.

Regarding the FXO port, the calling party does not receive a dial tone but a ring tone. The call is going to ephone-dn 22 because it is the best dial-peer match. There are several extensions with a button overlayed with dn 22 so that the call rings in every telephone:


ephone 7

mac-address 0019.55E6.47E9

type 7912

button 1o7,22,23,24,25,26,33,44,45,46




ephone 8

mac-address 0019.55B9.36B4

type 7912

button 1o8,22,23,24,25,26,33,44,45,46




ephone 9

mac-address 0019.55A9.5CC3

type 7912

button 1o9,22,23,24,25,26,33,40,44,45




ephone 10

mac-address 0019.55E6.5332

type 7912

button 1o10,22,23,24,25,26,33,44,45,46



I have been pushed to this configuration because the call coming through the FXO port does not carry any numbering information, and besides, there is not an operator but a pool of people to handle the calls.

jgolia Wed, 03/28/2007 - 04:29


I have heard the static you speak of and it was a u-law / a-law mismatch.


voice-port 0/2/0

compand-type u-law

Please rate helpful posts.



jgolia Wed, 03/28/2007 - 07:01

I agree for the PRI

The 4x POTS Nokia Premicell lines may be different.

A mismatch between a-law & u-law causes static.

Paolo Bevilacqua Wed, 03/28/2007 - 07:15

Sure, but no compand type can be set for analog ports. The system will automatically set the DSP attached to analog port, based on codec negotiated with the remote party.

Same with an all pots configuration (no actual voip), the system will again choose the appropriate compand type, a-law in this case.

I was recommending a THL sweep because the choice of complex2 impedance on FXO ports seem arbitrary, and should be tested with the real conditions expecially considering that a GSM adapter is being used.


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