Erdős Problem #48 — Infinitely many coincidences $\varphi(n)=\sigma(m)$

Are there infinitely many pairs of positive integers $a,b$ such that $\varphi(a)=\sigma(b)$? Equivalently, do the ranges of Euler's totient function $\varphi$ and the sum-of-divisors function $\sigma$ have an infinite intersection?