Is it possible to set up a silent call on asterisk?

Question

Asterisk

Good afternoon! Are there any options to configure asterisk (or on the phone itself) so that an incoming call to the phone (Yealink SIP-T21P) goes silent for the first 15 seconds (only line kei flashed), after which, as usual, with a beep.

Answer 1

New idea - using Alert-Info headers in SIP.
Something like this in Asterisk:

exten => s,1,SIPAddHeader(Alert-Info: silent)
exten => s,n,Dial(SIP/myphone,15)
exten => s,n,SIPAddHeader(Alert-Info: loud)
exten => s,n,Dial(SIP/myphone)

On the phone, set different melodies in the Settings->Melody section.
One melody with the tag silent , the second with loud . You may need to download a melody with silence to your phone.
or
Connect the phone with two lines to Asterisk. Insert a melody with silence on one line. Call the first line for 15 seconds, then the second.