The conjecture that Euler's totient has no nontrivial prime congruences

Let $p>2$ be prime, and let $A'$ and $B'$ be coprime integers. A Ramanujan-type congruence for Euler's totient function $cvarphi$ would have the form

$$\varphi(A'n+B')\equiv0\,\,({\rm mod}\,\,{p})$$

for every $n\geq0$. The totient congruence conjecture. There are no coprime integers $A',B'$ for which this congruence holds for all $n\geq0$. The claim expresses that Euler's totient function has no nontrivial Ramanujan-type congruences of this prime-modulus form; the source gives no resolution.