Hotline feature?

Is there a way to configure Asterisk so that in off-hook the phone will immidiately be connected or immidiatly dial to a specific line without having to dial anything? (for emergancy system so all phones in the system will be in this situation , no “normal” dialed calls)

Look for a phone which supports event driven programming. I.E. a pickup of the handset will dial a number and so forth. Once located give more details about what type of dialing you wish to have happen and we can create custom dialplan for this.

The phones are simple emergancy phones with no keypad to send the dial plan and they are connected to ATA which I’m not sure supports this option.
Any ideas what can be done?

Do these phones connect to Asterisk already? Can you provide a make and model?

This needs to be done in the ATAs. If the phones were analogue phones, directly connected to a analogue card on the Asterisk machine, you would have used the s extension, but with SIP devices, it is the SIP device that is normally expected to dial the number. (If the ATA can be setup to send an empty number, you might be able to use s.)

These are analog phones, I don’t have their model. They are connected to EdgeGate483D from Telco Systems which has two FXS ports (can be SIP or MGCP)

You need to configure the EdgeGate483D, not Asterisk.

If your ATA does not support autodial, you can try something like this.

I know but it seems that it can’t be done, this is why I’m looking for a workaround with the help of this communitiy

Asterisk can do nothing until it receives the SIP invite from the ATA. You must configure the ATA to send an INVITE when the line goes off hook. If that doesn’t have an empty user field, one can work round that, but without any input at all Asterisk can do nothing.