Short answer
No, and no service can: a fax is a dialogue between two modems, and a smartphone cannot take part in it. MondialFax therefore rejects mobile numbers at input, rather than accepting a send that is bound to fail.
A technical impossibility
A fax is a call during which two modems talk to each other: they recognise each other, agree on a speed, then transmit the pages as tones. At the other end, there has to be a device that picks up and answers in that language. A smartphone picks up and puts a person on the line: it cannot answer a fax.
Even a fax machine would not help
Mobile networks compress voice so that it stays intelligible at a low data rate. That compression destroys a modem signal: even if a fax machine were wired behind a mobile device, the fax would fail. This is not a commercial limitation; it is how the network works.
Why the form rejects mobile numbers
Rather than accepting a send that is bound to fail, MondialFax rejects mobile numbers at input. To get a document to someone on their mobile, use email or a messaging app; to let them know a fax is on its way to their office, a text message is the right tool.
Key points
- A fax cannot be received on a mobile phone.
- The mobile network destroys the fax's modem signal.
- MondialFax rejects mobile numbers at input.
- For a mobile: email, a messaging app or a text message.