Understanding The Mobile Part Of Mobile Phone

(I specialize in cell phones at my current place of work. One of my coworkers informs me of a customer asking about phones at the help desk. The operator relays this to me over the walkie.)

Operator: “Hey, I have a customer here asking about a phone that was placed on hold?” 

Me: “Well, I didn’t open today so it’s possible he placed one on hold before I arrived. Did he mention which phone it is?” 

Operator: “He says it’s a cell phone for [Cell Phone Provider]

Me: “Okay, but did he mention a brand? If it’s [Popular Brand #1], any of them can be used with any provider, but if it’s [Popular Brand #2], we have a specific amount in stock for that provider.” 

Operator: “Hang on; I’ll check.” 

(A few seconds pass:)

Operator: “He says it’s a portable one.” 

Me: “…” 

(The customer eventually came in. He was looking for a landline.)