Texting in Irish costs up to three times as much as English, because sending a fada uses up extra data.
Mobile phone users texting in the Republic of Ireland claim they are being ripped off for using the language and claimed it can be cheaper to send a photo than a fada.
Vodafone confirmed yesterday that users would be charged for three text (SMS) messages if they included a single 'sineadh fada' in a text of 160 characters.
Mobile phone operators blame the costs on technical reasons -- texts are charged according to the data used, rather than the number of letters or characters.
When mobile phone users switch from the standard English to use symbols from Irish or even another language such as Mandarin, this incurs a greater data cost.
A very short text, of less than 70 characters, can include multiple fadas and still be charged as one text.
However, additional costs arise if the text is what the industry considers a standard length, or 160 characters.
"If a customer is texting in Irish and they type the full 160 characters, a standard text message, that includes at least one fada, they will be charged for three text messages," a spokeswoman for Vodafone confirmed.
Both Vodafone and O2 said they conformed to the standards set by the European Telecommunications Standards Institute.
Gaelscoileanna Teo, a support body for Irish primary schools, said many Gaelscoileanna regularly send group texts to parents and only recently have become aware of the costs.
They said that the fada was an integral part of the language and the extra charge discouraged its correct use.
The official language commissioner, An Coimisineir Teanga, said they could not intervene as mobile phone companies were private businesses.
There has been no action taken by the Irish communications regulator, Comreg.
Daithi Mac Carthaigh, a former president of Conradh na Gaeilge, which promotes Irish, said Comreg had a statutory duty to protect the consumer.
Under regulations in Turkey, both mobile phone device producers and operators must allow the devices to use Turkish characters without an extra charge. Any devices that don't comply are not allowed on to the Turkish market. Similar initiatives have taken place in Spain and Portugal.