Keep modems silence and call back

I have my modems connected to a Remote Access Server (which is a Cisco Router
2610, IOS version 1.3). The model of modems as follows:

56K Faxmodem
Model: xx 5630-xx

I have 2 problems that I’d like you to help me:

1. I want the modems keep silence when a remote user get connected to one of them.

2. I want to call back to the user when they get connected to ensure that they just connect from a specific phone number.

I am using Cisco ACS 2.4 for Windows NT to authenticate the remote users.

Thank you very much for your help and waiting for your reply soon.