May. 20, 2026
Blocking spammy caller names with VoIP.ms Call Hunting
I made a small Rust VoIP.ms CNAME blocker.
The short version is that I wanted to block a caller by name instead of by phone number.
This sounds like it should be an option in VoIP.ms. For all the features VoIP.ms has, this is not one of them. So I made one for cheap.
The missing filter
VoIP.ms has a pretty capable CallerID Filtering feature. You can filter on specific caller ID numbers, phone book groups, anonymous callers, calls that do not match the North American number format, STIR/SHAKEN attestation level, and wildcard patterns like area-code-ish blocks.
That is all useful, but these asshole spam callers and scammers do not politely stick to one number. They rotate numbers. Blocking one just means the next call comes from another one. What I wanted to block on was the caller ID name.
VoIP.ms has CNAM support too, but as far as I can tell it is for displaying names, not filtering on them. Their blog post on stopping spam calls talks about filtering numbers, area codes, and anonymous callers, while describing CNAM as a way to identify callers before picking up. The Caller ID wiki page describes incoming Caller ID name lookup as an optional per-DID setting that can display a caller name for US and Canadian callers.