customer has Toshiba Strata with pots lines and many DKT phones and only 1 analog phone - polycom speakerphone
they have 2 RSTU2 circuit cards
recently the 1 analog extension was no longer able to break dialtone with touchtone
it can still receive calls
but previously it was able to dial extensions as well as 9 for an outside call
i've tried program 30 LED 11 and 31 LED 17
I've also tried replacing the RSTU2 card
still not able to break dialtone
please help

system reset and test again at the block with a 2500 set or buttset

RSTU2 cards are really old these days so you might have to replace it with another RSTU2 or RSTU3.
Have you got another RSTU2 card in the system that you could swap around to see if the fault follows the card or stays affecting the same port as it could be a programming issue.

Or try moving the RSTU to another slot. I've experienced this before on a DK.

There is a piggy back card on the processor that translates dtmf crcu-2 or something like that, the programming for the card has to include the piggy back in 03 I think. You can also turn system off reseat piggyback card and hope that fixes it

This sounds like a DK system. Have you tried running Ram Check prog 00 51 and 00 61?

The OP has not responded since the 3rd of April so I would presume he has fixed it by now.

Good suggestions by everyone hopefully stevenkaufhold will update the post to tell us what he had found was the cause.