Write down the pattern
Record when the fault began, the locations affected and whether it concerns voice, texts or data. Note recent device, SIM or software changes.
Check the basics once
Look for an official outage notice, restart the phone and check the selected line. If the SIM works in a suitable alternative handset, that may help narrow the issue; follow provider guidance first.
Protect account access
Never share passwords, one-time codes or SIM activation profiles with an independent information service. Lost or stolen phones should be reported through the provider’s official security route promptly.
Escalate clearly
Ask the provider for a fault reference and the next step. If it becomes a complaint, use its published complaints procedure and check the current alternative dispute resolution eligibility through Ofcom.
Take the next step carefully
This is general information, not account-specific advice. Check the official provider before changing service. For consumer switching and contract information, consult Ofcom’s switching guidance and contract change guidance.