A 40-year-old man has been arrested after a woman fearing for her safety dialled 999 and asked if she could order a pizza.
A call handler immediately asked the victim if she was in trouble and she replied, “yes".
The North Yorkshire Police operator establish the woman was on a bus which was located and stopped in the York area.
Officers detained the suspect, from Leeds, and he was taken into custody.
The control room handler realised the woman could only answer “yes” or “no” on Tuesday evening.
They worked out she was at risk of harm from a man travelling with her and kept the phone line open, texting for more information.
The bus she was on was identified through an online tracker and brought to a stop.
Inspector Dan Spence said: “This was really good work by everyone involved, allowing us to take immediate action to safeguard a vulnerable woman.
“I’m aware of people using the ‘pizza ordering’ technique abroad to contact the police, but I cannot recall a similar call in North Yorkshire.”
The man was subsequently released with no further action, although the woman has been provided with safeguarding and support.
All 999 calls are directed to call centres and answered by BT operators. They will ask which service you need.
If no service is requested but anything suspicious is heard throughout the process, the handler will connect to police.
A spokesman said: “It’s always best to speak to the operator if you can, even by whispering.
“You may also be asked to cough or tap the keys on your phone in response to questions.”