SMS delivery issues
What to check when text messages aren't delivered or contacts are excluded from an SMS batch.
Your SMS batch shows messages as sent but not delivered, or fewer contacts received messages than you expected. Work through the causes below in order — the first two account for most cases.
Sent vs delivered
Sent means Landing Zone handed the message off for delivery. Delivered means a confirmation came back that the message reached the recipient's phone. A message can be sent but never delivered — for example when a carrier filters it or the number can't receive texts — so a gap between the two counts is the signal to keep reading. See Understand a failed send.
Common causes
Your A2P registration isn't approved
SMS sending gates on an approved A2P 10DLC registration status. Check Settings → Trust Center for your current registration status. If it isn't approved yet, see the A2P 10DLC setup guide.
Landline or VoIP recipients
Landlines can't receive texts, and VoIP numbers are unreliable for SMS. Landing Zone classifies numbers as MOBILE, LANDLINE, VOIP, or UNKNOWN — verify line types before sending so you only text mobile numbers. See Verify phone numbers.
Carrier filtering
Carriers filter messages whose content looks like spam or whose volume spikes suddenly. Filtered messages typically show as sent but not delivered, with no error you can see. Keep message content plain and specific, and ramp volume gradually rather than jumping.
Quiet hours delaying sends
Messages aren't sent during a contact's local quiet hours — by default 9 PM to 8 AM in the contact's own timezone, configurable per workspace. A batch started in the evening may simply be waiting. See Quiet hours.
Contacts excluded before the send
Some contacts never receive a message because the eligibility check excluded them up front. Batch and campaign SMS require VERIFIED consent, contacts texted in the last 30 days are held back by the repeat-contact cooldown, and contacts on the suppression list are never messaged. Check the batch's pre-send preview: it shows an exclusion tally with the reason for each exclusion. See Consent and contact permissions.
Still stuck?
Email support with your workspace name, the affected batch, timestamps, and a screenshot of the batch preview or drilldown — see Contact support.
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