Why did artillery fire make wired communication unreliable on the Western Front?

On the Western Front during World War I, wired communication—which relied on an extensive grid of buried cables and telephone lines—was frequently rendered unreliable because the lines were physically severed by intense artillery fire.1

Despite efforts to protect these systems, the constant bombardment of the trench systems made maintaining the integrity of the wire network difficult at critical moments. This vulnerability forced belligerent nations to develop radio (wireless) technology as an auxiliary means of communication, though early radio sets were often unreliable and prone to enemy interception.12