"phone later on" is correct and usable in written English.
You could use it to suggest that someone should call you at a later time. For example: "Let's catch up soon, phone later on."
Nokia needs to keep budget buyers away from Android's low end — which sets consumers on an upgrade path to higher end Android smartphones — if it is to stand a chance of convincing them to upgrade to Windows Phone-based Lumia phones later on. .
"Well," Pat told me on the phone later, "at least they can't erase my film.
"I am overjoyed," he said on the phone, later in the day.
Next month, they release a carefully curated Best Of – Osman says on the phone, later, that Anderson has spent months labouring over it, making his own CDs to discover the best running order.
Erickson, who participated by phone, later issued a statement on behalf of the group. .
Or even called her on the phone later.
We've got Warren Barton on the phone later.
On the phone, later, Mr. Sides told us more.
"That's not so bad," my friend had commiserated on the phone, later.
On the phone later, Poehler, a lapsed Catholic, insisted, "It's not a cult!
