I had a case escalated to AE in which the question was how to dial an extension after dialing a phone number using an LQ attached to a matrix. The short answer is to add commas in between the phone number and the extension, IE

Each comma adds around 1/4 second of delay, so entering this would dial the number, wait around two seconds, then dial the extension. You will need to change this based on the needs of the conference you’re calling in to. This will work for both typing a number into an LQ and typing in a number into a speed dial in EHX. The only difference is that a speed dial in EHX cannot use any characters that are not a number, #, *, or comma. So your Speed Dial would look like this:

If you are calling in to certain numbers, especially for Teams and Zoom Calls, they often give you the correct notation in an email, because commas are also understood by mobile phones as a way to add a break between a phone number and its extension. If you have one of these “one tap mobile” numbers, you can copy and paste this directly to an LQ, or remove the - and + to add it to a speed dial.