Normal phone cables are of the RJ-11 type and fit in stationary or landline phones. There are other cable types for landline phones like the RJ-12 or RJ-45, which is the normal network cable connector known from computers. It is important to choose the right type.
If you are in doubt about what to choose, you can often read it in the specification on your product or on the manufacturer's website. Alternatively, our support is available on mail, chat and phone.