The Pepwave MAX 700 and On-The-Go feature multiple USB ports for fast and reliable mobile Internet.
Having 4 USB modems in a compact enclosure, the modems are placed very close to each other. However, the distance among the modems would not cause interference.
Carriers use different radio frequencies for transmission, and to avoid interference with one another. The proximity of USB modems will therefore not cause any interference. Just like having multiple lanes on a highway.