From the datasheet of a modem transformer we have:
- Impedance, Primary: 600 Ω Typ. @ 1 kHz 1 Vrms*
- Shunt Inductance Lp, Primary: 3.2 H min. @ 1 kHz
- D.C. resistance @20°C: Primary = 82 Ω ± 15%
Also the impedance formula:
$$ Z= \sqrt{R^2+(XL-XC)^2} $$
How does 600 Ω result from 3.2 H and 82 Ω? (The XC is negligible.)