How to make Asterisk 13 read DTMF "#" and save it to a variable?

Question

Asterisk

Good afternoon. Using the Read function, I read DTMF, but here's the trouble - you have to read the hash too (for Read, this is a sign to end). In my case, it is necessary to limit the number of DTMF or the duration of the combination input. How to be? Thanks in advance.