When you upgrade, the default is to hand the old iPhone over. Apple's floor for an iPhone 13 or later is $175 in instant credit. That is real money, and for most people it is the right call. But a working iPhone with a cheap line on it does something a credit cannot, and the numbers are closer than the checkout flow makes them look.
What a second line actually costs
These are current monthly rates from plans we track. Prices are the standard rate, not an intro teaser.
| Plan | Monthly | What you get |
|---|---|---|
| Tello Talk & Text | $8 | Unlimited talk and text, no data |
| Lycamobile $15 | $8 | 1GB, unlimited talk and text |
| Ting Flex | $10 | Pay-as-you-go data at $5/GB |
| Tello Starter | $10 | 1GB, unlimited talk and text |
| Red Pocket Essentials | $10 | Small data allowance, unlimited talk and text |
| Ultra Mobile Talk & Text | $10 | Unlimited talk and text, no data |
A spare iPhone on Wi-Fi at home needs no data at all, which is why the talk-and-text tiers are on this list. Ting Flex is the one to look at if the phone leaves the house occasionally — $10 covers the line and you pay $5 per gigabyte only in the months you use it.
What the second line is actually for
- A number you give out. Marketplace listings, service bookings, anything you would rather not attach to your real number.
- A work line that can be switched off at 6pm, on a phone you already own.
- A kid's first phone. An old iPhone on a talk-and-text plan is the cheapest supervised starting point there is.
- A spare that already works. If your main phone is lost or broken, an active line on a second handset means you are not offline while you sort it out.
- A coverage test. Put a cheap line from a different network on it and find out whether that carrier works at your house before you move your real number.
Which carriers let you try the network first, and for how long.
See the trials →When to take the credit instead
Most of the time. The second line only wins if you will genuinely use it, and a line nobody uses is $120 a year of nothing.
- The phone is damaged. Trade-in value drops sharply with condition, but a carrier deal takes an iPhone 14 or later in any condition — that is worth more than a spare handset.
- The battery is finished. A phone that cannot hold a charge is not a usable spare, and a replacement battery eats the saving.
- It is an iPhone 13 or older. It still trades in, but it will start losing iOS support before a newer one does.
- You have no use in mind. Be honest here. If you cannot name the thing the line is for, take the $175.
The version of this that pays for itself
There is one case where the second line is straightforwardly better value: replacing something you already pay for. If the spare iPhone becomes the kid's phone instead of a new handset, or takes over a work line you currently pay $30 or more for, an $8 to $10 plan is a saving from month one and the trade-in credit never enters into it.
Jean Gilles has researched personal finance, consumer technology, and wireless pricing for over a decade. He founded ShopCellPlans in 2019 and writes every review on the site.
Frequently asked questions
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