I needed to replace both the wall cord and the handset cord. Both were badly cracked. The new cord was 10 feet long, so I needed to cut it into two lengths and transfer the four strain-relief clamps from the ends of the old cords to the new ones. The phone works great now. Only caveat (for the purist) is that the new cord, while looking similar to the original, is somewhat thinner.
Black rubber line cord that's round and flexible.
3 conductor. Comes in 2 different lengths and is spaded cord.
Black rubber line cord that is round is hard to find because its no longer being made
This is your best bet.
Could be used as a 3 conductor subset cord also. These are new old stock found in packages
We have 10ft and 12ft left in stock . If you need 7ft you will have to cut them smaller
I'm glad to find a NOS item. The price is right