asterisk users - Dec 2006 - Modem Dial-up internet connection thru Asterisk with T1-PRI

We have a PRI line setup on an asterisk box. 
I want to provide a couple dial-in lines for internet access from our remote
offices. 
The remote offices only have analog lines. 

I thought I could do this with the ZapRAS or PPPD functions in Asterisk, but
the more I read this is only for ISDN connections on both sides. 
Is that correct? 
Does anyone know how to accomplish what I'm needing to do?

Thanks!