Vodafone Egypt says the advert, featuring the puppet Abla (Aunt) Fahita, is merely a marketing tool and has no hidden message or meaning.
The case stems from claims by a political activist who calls himself Ahmed Spider that next week's Coptic "Christmas day will be a bitter day because of explosions (planned) by anarchists with the help of (ousted president Mohamed) Morsi's supporters."
Copts, who make up the majority of Christians in Egypt, celebrate Christmas on January 7.
In his remarks to private television channel Tahrir, Spider said the four branches of a cactus used as a Christmas tree in the advert symbolise the four-finger Islamist salute used by ousted president Mohamed Morsi's supporters.
Spider, an avid supporter of ousted president Hosni Mubarak, also said an ornamental ball dangling from the tree represents a bomb, while stuffed turkey breasts spoken of in the commercial symbolise "car bombs."
Yesterday, prosecutors summoned Vodafone executives for questioning following the complaint.
"Our marketing director went with our lawyer to the prosecution," Noha Saad, head of Vodafone's public relations told AFP today.
"The prosecution heard their statements in response to the complaint filed by Ahmed Spider. There were no accusations by the prosecution. They are in the phase of gathering information."
Speaking on another show broadcast by private television channel CBC, Spider also accused "British intelligence services" of being behind it all.
And addressing Abla Fahita, he repeatedly threatened to send her behind bars after she poked fun at him.
"I will jail you or I will leave the country," he said.
The advert is for an offer under which Vodafone customers can re-activate their old SIM cards.
A company statement said "any other explanations are pure fiction and personal opinions of some viewers and Vodafone is not liable for the personal attitudes and interpretations that are far from reality."
Spider's allegations have prompted some sarcastic comments on social network Twitter.