First off it doesn't have the circuitry to connect to a plain old telephone line. So we're stopped right there. Is there more to your story why you want to do this or is this the old why can't it be done question that you can ask of anyone?
If you need more answers to this, try it at the usual cell phone stores. If it was possible they would sell it to you.
I know of that link 2 cell system, but your question is not about that. As an electronics designer I'm sure that we can design something that will fix the issue but my bet is that cost is an issue. That is, a new design seems to run nearly a million. It may be time to replace that device?