There is an extra step. Long press the phone number to select it. Depending on how it was formatted in the page, you might need to adjust the start and end points of the selection. On the top bar, look for the expansion menu (3 vertical dots) and tap that to get a "Call" item.

bischy1 said

when using my cell phone company's browser,when i go onto a web sight, and it has a phone number,i can touch the number and then it brings me to the dial part of the phone,where i can then either call or text the person,how do i set the same up using firefox???

thank you very much, that worked