As a journalist Steve Earl did his fair share of doorstepping and dustbin scavenging during the early 90s. Sometimes the role of a journalist investigating a big story skirts close to the tolerance of the law.

Details of how the mobile phones of people in the public eye were allegedly “hacked” by journalists at News of the World as reported by the Guardian today remain undisclosed. But one of the questions any ongoing investigation will no doubt ask include whether what is claimed to have happened was hacking per se, and whether it broke any laws.

Without making any inference whatsoever on the allegations currently facing individuals at the News of the World, here are some possible ways that an individual could conceivably, if they were so minded, get information from mobile phone services:

• Bug on the handset – unlikely that anyone would go this far and difficult to implement en masse anyway
• An intercept during the conversation – difficult and expensive, requiring military-level expertise
• Phone company insider – paid to listen-in or record calls, or provide access to voice packets or voicemail files
• Voicemail hacking – each network has a default voicemail pin. If you don’t change your pin, your messages could be hacked anytime your phone is switched off or you miss a call. You could call this hacking, but it could be viewed as the equivalent to leaving a window open

Two things surprise me about this case: how quick other publishers have been to turn on News International, publisher of The News of the World, The Sun and The Times, and that journalists at the News of the World would risk using such a tactic after seeing a colleague and private investigator jailed for a separate but phone-related incident in 2007.