When use FLASH on a FXS DAHDI channel, it doesn't transfer

When user press FLASH, hookflash doesn’t break dialtone, instead is possible to see on the console the following message:

[Feb 1 15:35:28] DTMF[21958]: channel.c:4109 __ast_read: DTMF end '1' received on DAHDI/70-1, duration 0 ms [Feb 1 15:35:28] DTMF[21958]: channel.c:4135 __ast_read: DTMF begin emulation of '1' with duration 100 queued on DAHDI/70-1 [Feb 1 15:35:28] DTMF[21958]: channel.c:4271 __ast_read: DTMF end emulation of '1' queued on DAHDI/70-1

It is like hookflash is sending “1”.

Even with threewaycalling=yes and transfer=yes on chan_dahdi.conf isn’t possible to transfrer using flash.

Asterisk 1.8.32.3

Sounds like you have a phone conifigured for the UK timed break recall standard, rather than the US hook flash. UK timed break is essentially the same as a pulse dialled “1”. US flash is a lot longer.