The max distances may be short if you use an UTP cable as E1 crossover, but the max distance is 600m for unbalanced BNC cable.
Crossover:
http://wiki.sangoma.com/Cablepinouts#t1_e1_cross
"The VWIC-MFT-E1 receiver operates in a short haul mode and can recover a 20-decibel (dB) attenuated signal. In order to translate this to an accurate cable length, you need to know the cable attenuation characteristics. Typical cable attenuation for .4 millimeter (mm) wire is 3 dB per 100 meter (m) (measured at 1024 kilohertz [KHz]). So the maximum cable length for this card is approximately 600 m. This value includes a 3 dB margin"
http://www.cisco.com/en/US/products/hw/routers/ps274/products_tech_note09186a00800b6e0f.shtml
