When an extension is unavailble, allow the caller to call any extension he likes: How can this be done?

I installed all latest versions and played a lot with the FollowMe, VmxLocater and IVR. I couldnt find solution

  1. Imagine a “PSTN caller” calling. The default extension (100) is ringing.
    I would like after several seconds if 100 is unavailable, with no voicemail, the tone signal of the freePBX to be heard to the “PSTN caller” and with/without a message the “PSTN caller” can dial again any other inbound extension without need to hang up.

  2. Why does the SPA3102 makes a lot of time ~10seconds to respond to opening the PSTN (dialling 9) ? When I transfer a call to SPA3102 ATA takes less than 1sec. When the PSTN calls the freePBX the default extension 100 rings at once.

Thanks in advance

for #1. a ring group will allow a series of extensions or dialable locations to be called in sqeuence and if nothing happens at those extensions then you can say what to do next. So knowing that create a IVR giving them access to do what you want. Like get the company directory, etc. Then direct the calls into the ring group which falls through to the IVR.