[cisco-voip] router 1841 or 1760 as a voice gateway?

[Fernando Rojas]

Reading Cisco documentation , I see that router 1841 and 1760 does not
support as Voice Gateway for a Primary ISDN access.

My idea is to connect to him a Primary ISDN (30 channel B) so that it
works like a PBX (using CallManager Express) and users can make calls
towards PSTN.

There are any way do this with these routers (1841 or  1760)? 

Otherwise that is the minimun cisco router plataform to use a Primary
ISDN (30 channel B) for the topology that i want to build. ?

Thanks