In my locale, ISDN is offered at a "base price" almost exactly the same as the "base price" for two separate POTS lines. I've asked, but can't get useful information from the providers:
1. Your installation order is assumed to be a "verbal contract" but they refuse to provide a copy of the contract prior to installation.
2. Additional hardware is required, but the refuse to provide even a generic description of what hardware will be required/used.
3. Additional hardware may require purchase or lease fees, but they refuse to provide any information on such costs in advance of installation.
4. A specific ISP must be used, and a long-term contract is implied, but they refuse to reveal the terms prior to installation.
5. Specific software must be installed on your computer, and they refuse to provide even a generic description prior to installation.
... I could add another several items, but have to ask - doesn't it look like I'm dealing with a bunch of swindlers if I sign up? I'm pretty sure it would cost more than what's quoted in their frequent (and frequently changing) ads.