56k modems relied on digital trunk lines

Role of Digital Trunks in 56k Modems

• Several commenters argue the headline is slightly inverted: digital trunks initially limited throughput because voice-oriented A/D conversions mangled high‑rate modem waveforms.
• ISPs and servers were already on fast digital IP networks; the analog “last mile” could, in theory, carry ~56 kbps using special encodings.
• The problem was the phone backbone’s 8 kHz, μ‑law/A‑law, DS0/ISDN voice framing: multiple analog↔digital conversions broke the 56k signal.
• V.90‑style schemes worked by feeding digital data directly into the phone network at the CO and keeping it digital until the last analog hop.
• This only worked in one direction (downstream). Upstream still passed through traditional A/D paths, capping uploads at 33.6 kbps (later ~48 kbps with V.92 tricks).

Line Conditions and Real-World Dialup Speeds

• Many users recall being stuck around 26.4 kbps despite “56k” modems.
• Causes mentioned: extra A/D conversions, pair gain systems, bridge taps, load coils, narrowband amplifiers, echo cancellers, and generally poor outside‑plant copper.
• People describe telcos being unmotivated to fix lines for internet use; claiming fax problems sometimes forced them to re‑engineer circuits.

ISDN, Latency, and Early “Fast” Home Links

• ISDN (64 kbps per B‑channel, 128 kbps bonded) is remembered as a “gold standard”: low latency (sub‑20 ms), instant call setup, and simultaneous voice/data.
• Downsides: per‑minute billing, expensive tariffs, and deliberate discouragement by incumbents, which limited consumer adoption.
• Still heavily used for remote admin and high‑quality broadcast audio; some lament that today’s radio/phone interviews often sound worse.

ISP Gear and Numbering Tricks

• CO equipment often terminated multiple analog lines into racks of modems, later replaced by digital access servers that emulated many modems over a single T1.
• This digital termination on the ISP side was essential for true 56k.
• Toll‑free and nationwide dialup numbers were frequently routed to local POPs using intelligent-network routing based on caller location.

Copper vs. DSL/Fiber and Broader Reflections

• Commenters debate claims that “ordinary copper can do 1 Gbps”: technically plausible only over very short, clean runs; real loops with stubs, splices, and noise are far worse.
• xDSL is framed as using the same pairs but bypassing voice‑band constraints, with FTTN/FTTC seen as transitional before full fiber.
• Strong nostalgia for modem handshakes, “shotgunning” dual modems, Ricochet wireless, and the era when web pages had to fit within tens of kilobytes.