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How to fix a speed of a mica modem


I've a 3745 router (IOS 12.2(11)T9) with a mica-6DM (Portware 2.7.3) integrated.

I've some application that only work at a speed of 2400 bits/s and consequently I want to fix the minimum and maximun speed at 2400.

The problem is that it's running fine during some days and suddenly the speed is changing automaticaly for no apparent reason. Can you help me to solve the problem ? Below you find the important point of my configuration.

aaa new-model


aaa authentication banner ^C^C

aaa authentication login BONE group radius

aaa authorization exec BONE group radius

aaa accounting network BONE start-stop group radius

aaa session-id common


modem country mica spain


isdn switch-type primary-net5


modemcap entry mcom:AA=S30=2400S31=2400


controller E1 1/0

pri-group timeslots 1-31


interface Serial1/0:15

no ip address

isdn switch-type primary-net5

isdn incoming-voice modem

no cdp enable


radius-server host auth-port 60005 acct-port 0

radius-server key 7 <removed>

radius-server authorization permit missing Service-Type


line 97 126

exec-timeout 0 0

no flush-at-activation

authorization exec BONE

login authentication BONE

modem Dialin

modem autoconfigure type mcom

escape-character NONE


Re: How to fix a speed of a mica modem

The workaround is to use a modemcap using a different value of S29, and/or S30 to limit the top rate, and/or S64 to use a fixed modulation. Examples:

modemcap entry v22bis:MSC=&f&d2s29=4

This will automode with the top modulation being V.22bis (2400 bps)

So try to change the value of s29=4 , this mayfix your problem

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