Or, alternatively, you could be on what some people consider to be the most evil thing ever invented: a conference call!
But what to call those non-landline devices that we seemed to be glued to? It can take a picture, record a video, take you to the internet, has game apps that will keep your toddler (or bored teenager) out of your hair for five minutes, and, in some instances, has actually been used to place a phone call to someone!
In wonderful English language tradition (can you hear the sarcasm there?), it's either a smartphone (one word) or a cell phone (two words). Merriam-Webster has the same basic device with two different approaches: a one-word and a two-word form.{Yes, I know...some will call it a mobile phone.}
Does it make a huge difference if you used cellphone and smart phone instead? Probably not...the reader would still know what you mean. But it should at least be consistent in your manuscript. (And if I am lucky enough to read through your manuscript, it'll be cell phone or smartphone, just like Merriam-Webster likes it!).