You don't need to hack your firmware to install other dialers. There are dozens on the android market.
Edit: Dialer One's release notes for v1.2 say that an issue was fixed regarding United States emergency numbers. Not sure if that pertains to this issue, though.
Edit: Dialer One's release notes for v1.2 say that an issue was fixed regarding United States emergency numbers. Not sure if that pertains to this issue, though.