To an extent, but the simple employment of Anti-tank guns is not enough. The defense of Kursk was so successful largely due to the defense in depth. There are many other factors (such as the Soviets having some knowledge of the offensive before hand), but the Soviets establishing a defense in depth greatly aided their efforts to blunt an armored spearhead in the Kursk sector. (I use the term 'armored spearhead' with a stretch, as well, the first wave of attacks consisted largely of Infantry units)

The rule of 'defense in depth' can generally be applied to all forms of warfare, but its doubly-true for anti-tank warfare. Armor needs to be separated from its infantry support through vigorous use of small arms and artillery of all calibers, so that the tanks can, theoretically, be destroyed by concealed anti-tank guns, layered in defensive belts in depth, as the enemy armor advances without its eyes and ears and into compromising situations.

The simple employment of Anti-tank guns and anti-tank mines means nothing if the enemy can bring enough fire support to cover engineers to remove the mines and if a defender cannot disrupt tank-infantry co operation to a sufficient extent. In the case of Kursk, the Soviets were successful in frustrating German attempts to sufficiently clear anti-tank obstacles.

Lastly, you are both correct and incorrect on the statement 'tanks are not the best defensive weapon.' Define defense. If you employ them in largely static positions, even with further fortifications and tank dug-outs, you are still robbing a tank of its number 1 asset: mobility. Tanks can be used very effectively in defense if kept in a tactical or strategic reserve, and be used to counterattack any exhausted spearheads that manage to hammer their way through a series of defensive lines. The Germans, prior to Kursk, largely prevented their lines from collapsing in the Southern USSR and Ukraine from such strategically 'defensive' use of tanks. Sometimes the best defense is a well-timed counter-offensive.

EDITED: Grammar, Spelling

Britain OP offers a good examination of a combined arms defense-in-depth, but there is another consideration: Tanks were designed to be mobile. Putting a tank in good defensive position really just turns that tank into a glorified AT gun. Tanks are designed to move around, hit the enemy in their vulnerable places, and exploit breakthroughs caused by other units. They are, at their heart, offensive weapons which may also be used in defensive roles. So, when conducting BritainOPs defense in depth, most of the tanks would be held in operational reserve, while the infantry and "fixed" guns would do the messy work of slowing the enemies initial thrust. Now the attacker would inevitably capture some defensive positions, but as their attack slowed, the tanks would generally would switch from reserve to counter-attack. This is exactly what happened at Kursk, and led to the famous tank battle at Prokhorovka. However, the role of the tank doesnt start or end with the blunting of the enemies attack. They armored counter-attack, where successful, becomes the starting points for a seamless switch to the operational offensive.

If you examine the Battle of Kursk, it is the ultimate example of a Soviet style armored defense. We often remember the German Citadel attack, which only managed to penetrate a few kilometers into the Kursk Salient. This was due, in large part, to the defensive measures mentioned in BritainOp's post. The ultimate deathknell of the operation was the battle at Prokhorovka, where the Soviets stemmed the deepest German penetration. The Soviets quickly used their success on the defensive to unleash a large number of armored units, held in reserve during the battle, to counter-attack the German forces. This quickly turned into a full scale assault, in the form of the Kutuzov and Polkovodets Rumyantsev offensives, in which the Soviets smashed the German forces opposing the Kursk Salient.

That is how tanks are conventionally employed in defensive roles, acting as a tactical and operational reserve to be unleashed at the very moment the enemies attack begins to waver.