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Consolidation of dial-in users and ISDN on one PRI INt at central site

I have a project to consolidate all our remote access systems. We have ISDN on one system, dial-in users on another, and dial-out users on yet another system. I want to consolidate all these systems to one. I also want to use one PRI connections to my local PSN. I have purchased a 3660 router with dual PRI module (NM-2CT1). In my reading, in order to consolidate asychonous and ISDN traffic over one PRI interface the router need to have a modem card. is the true? if so, what is require or minimun hardware needed. If not can you refer me to documentation I can use to complete my project.

Cisco Employee

Yes you need MICA modems in your 3660 for both inbound analog and outbound analog calls. Depending on what percentage of your users is analog, you can

either order NM-12DM (12 MICA modems) , 18DM , 24DM

etc. Make sure you are running some latest 12.1 image along with MICA modems portware rev 2730. For a sample config on how to do inbound async/isdn and outbound dialing, please see the following:




hello, thank you very much for your response. I have a follow up question. If I go with the NM-12dm module, and this may be an obvious answer but I need to ask anyway; How many asycn and how many ISDN connection can be active at one time? am I right to think 12 async and 12 bri connections? is it safe to assume this many?


3600 can support max about 4 T1 lines but max of 60 mica modems..So i think max 48 modem connections along with 48 isdn connections is the total capacity.Tejal

Cisco Employee

Hi Hector,

YES..You are correct..You do need the modem cards (which should be digital modems) in the router to terminate the modem calls coming in over ISDN PRI line. You can order the digital modem called "mica modems" for 3660 router which had module name NM-xxDM..Where xx is the modem numbers multiple of 6.

Like NM-6DM, NM-12DM etc..

3660 will do the job what you are looking for as a minimum.

Here is the url to visit to know more about 3600

For different configs with 3600 router, pl. visit at


Tejal Patel


If your follow up question relates to one PRI, then

ofcurse a PRI has 23 B (user) channels. So if you

have an NM-12DM card, then at any given time, the

full PRI may have users in the following manner :

(1) max of 12 modem users + max of 11 isdn users =23

(2) o modem users + 23 isdn users. =23