The device has many names in different parts of the world: cell phone, cellular phone, cell, handphone, handy, mobile phone, mobile, portable, and so on. On the other hand,
- cellphone refers to cellular technology, and is not technically accurate for satellite phones or portable IP phones. It is still the primary term in North America but is no longer elsewhere (even in Latin America, telefonía móvil seems to be displacing telefonía celular).
- handphone is the standard term in East and Southeast Asia, but does not seem to be common in English-speaking countries elsewhere.
- the abbreviations like cell or handy are too ambiguous to be useful tags.
On the other hand, I think the term mobile phone is clear and well-understood. It is the common usage in Europe, but also the more universal-- you'll find cellphone and mobile or handphone and mobile used together, but quite rarely cellphone and handphone. And for the pedants, it would cover both satellite and cellular phones and any other mobile technology we may devise moving forward.