Hey 6839470,
I would get a 2501 or 2503, the 2524 is a modular router and the 5 in 1 serial interface for it will cost as much as the router, unless you find one with it already, most I see on Ebay have just the ISDN module.
The whole idea is to get several and connect the seral ports and set up routing.
Both the 2501 and 2503 have 2 serial interfaces in addition to the 1 ethernet aui.
As I have told others - read ad carefully and then go to Cisco or Google and search for what it is you want!!!
From Cisco on the 2524 and 2525 routers -
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Overview of the Cisco 2524 and Cisco 2525 Routers
The Cisco 2524 and Cisco 2525 routers provide LAN and WAN access in a low-cost modular router platform that can grow with your internetworking needs. The Cisco 2524 offers an Ethernet (attachment unit interface [AUI] or 10BaseT) LAN connection, and the Cisco 2525 offers a Token Ring (shielded twisted-pair [STP] or unshielded twisted-pair [UTP]) LAN connection. Both routers can accommodate up to three WAN modules--two synchronous serial and one Integrated Services Digital Network (ISDN).
The choice of synchronous serial WAN modules is as follows:
2-wire switched 56-kbps data service unit/channel service unit (DSU/CSU)
4-wire 56/64-kbps DSU/CSU
Fractional T1/T1 DSU/CSU
Five-in-one synchronous serial
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Good luck !!!!
E.A. Broda
CCNA, CCDA, CCAI, Network +