There should be a p/t switch on the side of the phone. Slide it to t for tone.
These units just have a small switch on the side of the handset with two positions for pulse or tone, just to the left of the earpiece Here is the link to the instruction manual for your phone; http://www.swbfreedomphone.com/ib/ibcord/fc2548.pdf Check page 2 of the pdf file if you are struggling to find the switch. Hope this helps :)
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