There are several solutions, here are 2. You could create it with a Curve modifier or with Spline IK. The second solution is bit more complicated but it will probably give a better result.
Also, I explain how to create bone controllers for each handle of your curve: it's useful when you want to animate or even keep a basic reset shape for your curve.
With a Curve modifier:
- Create your cable profile, it looks like a rectangle, shift it a bit from its origin. In Object mode apply the rotation of the object.
- Give it a Screw modifier, play with the parameters.
- Create a curve, flatten it, subdivide it a bit, make its origin begin at the same point as the cable origin, make sure its normals direction goes in the right direction, if not switch with W > Switch Direction.
- Give your cable a Curve modifier, choose the curve as Object.
- Now if you bend the curve, the cable will follow.
- To give a bit more smoothness to your cable, bevel its profile vertices with a shiftctrlB.
- Give a Subdivision Surface modifier to the object.
- Now your cable is ready, you can apply the Screw modifier and parent the phone handset to the vertices of the cable end, or you can try to keep the Screw but I guess it will make the handset setting more complicated.
- To animate you can hook the curve handles to bones, as explained further, or to empties.
With bones and Spline IK, as explained here by Peter Drakulic:
- You've made your object and your curve (see beginning of method 1). Apply the Screw and Curve modifiers of the object if you want. Keep the curve.
- Add a bone as long as the curve, subdivide it a bit.
- Keep your armature selected, switch to Pose mode and give the top bone a Spline IK constraint with the curve as Target and the number of bones as Chain Length. Deactivate the Y Stretch option. Now when you move the curve the bones follow.
- Parent the object to the armature With Automatic Weight. Put the Armature modifier above the Subsurf. Activate the Preserve Volume option of the Armature modifier.
- Again, to animate you can hook the curve handles to bones.
You may want to create some bone controllers for each handle:
- Create a new armature with each bones at the exact same point as each handle.
- Switch the armature to Pose mode.
- Select one of the bones.
- Press shift and select the curve.
- Go in Edit mode and select the corresponding handle.
- Press ctrlH > Hook To Selected Object Bone.
- Same thing for the other bones.
- Now you can control the whole curve with this armature.