Setting up a child's first SIM

Setting up a child’s first SIM takes one quiet evening. Fit the card, activate it the day before it’s needed, keep an existing number with a free PAC code or start fresh, pick a plan that can’t silently run out, save five contacts, and test one call and one text before you hand the phone over.

Get the SIM size right

SIM cards come in three sizes: standard, micro and nano. Check the phone’s SIM tray or manual before you push a SIM out of its frame, because a punched-out SIM doesn’t go back together. If the pack carries more than one size, push out only the one it needs. Choosing the handset too? Start with our Nokia 3210 review.

Activate it the day before, not on the day

An inactive SIM is just plastic. Each provider has its own activation steps, in the pack or on its site, and don’t bank on them being instant. Activate the evening before, not at 8.15am on day one. The four SIMs in our ranked guide (ParentShield, Smarty, Lebara, giffgaff) are all monthly with no fixed term, so a day early ties you to nothing.

Keep their number, or start fresh

If your child already has a number worth keeping, from a hand-me-down phone say, Ofcom’s text-to-switch scheme makes it simple. Text PAC to 65075 from the old SIM, free on every UK network. The code is valid for 30 days. Give it to the new provider and they complete the switch within one working day. For a clean start, text STAC to 75075 for a new number. A genuine first phone usually has no number to keep, so use the one that comes with the SIM.

Set the plan so it never runs dry

The failure mode is a phone that’s out of credit when your child needs to call you. Two ways to rule that out. A rolling monthly plan renews itself: Lebara from £4 a month on Vodafone, Smarty from £6 on Three, or ParentShield from £9 on EE with its whitelist and call logs. Or take the hard spending ceiling of pay as you go and switch on auto top-up, so the credit refills itself. We weigh the two routes in PAYG vs SIM-only, and for no mobile internet at all, see our calls-and-texts-only guide.

Save five contacts before you hand it over

Do it while the phone is still in your hands: both parents, the school office, a grandparent, one friend. Five numbers, labelled plainly (Mum, not a nickname), with a parent at the top of the list. On a basic phone with no contact history, those five are what the phone is for.

One test call, one test text

Have your child call you from the new phone and text you, then do the same back. Two minutes, and it confirms three things: the SIM is active, there’s signal where you live, and your child knows which buttons do what. If the phone has an SOS or speed-dial feature, set it now while you’re both looking at the handset.

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Common questions

How do I keep my child’s existing phone number? Text PAC to 65075 from the old SIM. It’s free on every UK network under Ofcom’s text-to-switch scheme. The code is valid for 30 days. Give it to the new provider and they complete the switch within one working day.

What size SIM does a child’s basic phone take? Check the phone’s SIM tray or manual first. SIM cards come in standard, micro and nano sizes, and a punched-out SIM doesn’t go back together.

When should I activate the SIM in a child’s phone? The day before it’s needed, not on the morning itself. Don’t bank on activation being instant. The four SIMs we rank are all monthly with no fixed term, so a day early costs nothing.

Which SIM should go in a child’s first phone? ParentShield at £9 a month on EE for a whitelist of allowed numbers and call logs sent to a parent. Smarty at £6 on Three for a cheap no-frills plan. Our best SIMs guide compares the four we rank.

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Next steps: pick the SIM in our ranked SIMs guide, then the rest of the back-to-school first-phone checklist.