Comment by rwmj
The closest parallel is probably with the dot com bubble where some companies (notably Cisco & IBM) loaned money to purchase network equipment to their own customers. Since those customers weren't profitable (or arguably even financially viable companies at all) the whole thing exploded rather spectacularly.
Cisco probably did the least bad out of all those telecom/networking companies, and I don't think IBM was ever a big player. So many companies saw the start of their demise then--Lucent, Nortel Networks, Ericcson, etc.