[grogenaut]

megacorp I work for solves this by automatically escalating pages up the org chart every 30 minutes using LDAP when a page isn't acknowledged. while this seems scary, it makes the managers have a pager (and feel the pain, many actually get paged when the engineers get paged just so they know things are breaking and how bad the tech debt is). It also means you don't need to have a secondary, the manager just doles it out if it gets lost.

It has other big benefits, it lets N+1 tier know when tier N doesn't have a pager setup. Sometimes this is the engineers, but it gets real fun when a Director or VP gets paged, ops culture sharpens up very quickly. It also forces the managers to buy in to oncall as I said, which is a good thing imho.