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Will you please help me to solve the following problem?

Two HWIC-3G-GSM modems (Sierra MC8775) have been installed in Cisco Router 2851 (iOS 15.1(4)M7)

In each modem has SIM cards of different operators

Modems` versions   - firmeware 2.08.19.

Modem connection is establishing but is breaking off because of unaccountable reasons

The lost the connection can occur in 5 minutes after switching on, as well as in 2 or 3 hours.

The following information is displayed In debug :

Dec 8 18:03:53: %LINK-3-UPDOWN: Interface Cellular0/0/0, changed state to down

Dec 8 18:04:03.029: Ce0/0/0 DDR: re-enable timeout

Dec 8 18:04:03.877: Ce0/0/0 DDR: place call

Dec 8 18:04:03.877: Ce0/0/0 DDR: Dialing cause ip (s=, d=

Dec 8 18:04:03.877: Ce0/0/0 DDR: Attempting to dial mts

Dec 8 18:04:03.877: CHAT0/0/0: Attempting async line dialer script

Dec 8 18:04:03.877: CHAT0/0/0: Dialing using Modem script: mts & System script: none

Dec 8 18:04:03.881: CHAT0/0/0: process started

Dec 8 18:04:03.881: CHAT0/0/0: Asserting DTR

Dec 8 18:04:03.881: CHAT0/0/0: Chat script mts started

Dec 8 18:05:03.876: CHAT0/0/0: Chat script mts finished, status = Connection timed out; remote host not responding

Dec 8 18:05:03.876: Ce0/0/0 DDR: disconnecting call

It`s necessary to reload cisco due to reinstall the connection again


chat-script MTS "" "ATDT*99***1#" TIMEOUT 60 "CONNECT"


interface Cellular0/0/0

ip unnumbered Dialer2

ip nat outside

ip virtual-reassembly in

encapsulation ppp

load-interval 60

dialer in-band

dialer pool-member 2

dialer-group 1

async mode interactive

ppp chap hostname mts

ppp chap password 7 11040D16

ppp ipcp dns request


interface Dialer2

ip address negotiated

ip nat outside

ip virtual-reassembly in

encapsulation ppp

dialer pool 2

dialer idle-timeout 0 either

dialer string MTS

dialer persistent delay initial 2

dialer-group 1

ppp chap hostname mts

ppp chap password 7 11040D16


line 0/0/0

script dialer MTS

login ctrlc-disable

modem InOut

no exec

rxspeed 7200000

txspeed 384000

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