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Use an admin-scoped API key for these endpoints. Agent-scoped keys receive 403. You can also manage billing in the Inkbox Console.

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Check custom signature availability

Use the top-level mail_custom_signatures_enabled boolean in the subscription response to check whether your organization can configure automatic custom email signatures. This reports feature availability, not an individual mailbox’s on/off preference. Paid subscription details also include entitlements.mail_custom_signatures_enabled; entitlements may be null, so use the top-level field for this check. On paid plans, entitlements.plan_amount_cents is the flat plan fee only and excludes call-minute packs. entitlements.voice_packs lists every pack size with your current quantity, or is null when packs aren’t offered. Each entry contains pack, minutes, price_cents, and quantity.
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Configure content and the mailbox toggle through Update mailbox. Disabling or clearing a saved signature remains available even when this feature flag is false.

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Read current usage

Returns usage for your organization’s current billing cycle. Incoming and outgoing SMS/MMS share one organization allowance. Incoming and outgoing call seconds share another. Usage without an attached identity draws from the same organization pools. The included voice allowance is an organization-wide total shared by VoIP and iMessage calls. Adding identities does not multiply the standard allowance. The standard SMS/MMS allowance scales with included VoIP phone-number capacity. Custom allowances and existing grants can change your organization’s total; use the returned organization allowance fields for its effective limits. Included SMS/MMS and call-minute allowances, and the listed overage rates, cover U.S. and Canadian numbers. International texting and calling use international lines with pricing by country. See Plans and pricing, or contact us to arrange an international line.
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Response (200)

Each entry in channels contains: Each entry in identities contains nullable identity_id, handle, and display_name, plus a channels array of event_type, count, and own_campaign_count. Its nullable sms_used and voice_sec_used fields report actual activity. The deprecated sms_limit and voice_sec_limit fields return 0 when present: no allowance is separately reserved for an identity. A null identity ID represents unattributed usage. Use the organization *_remaining fields for available included usage. Do not sum the deprecated identity limits. Voice usage consumes included seconds before any available minute packs. Existing charges are not recalculated when allowances change.

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Buy call-minute packs

Call-minute packs add recurring call minutes to a paid plan. Use them when your agents regularly use more call minutes than their included allowance. Packs aren’t available on the Free plan. You can hold up to 100 of each size. Pack minutes form one organization-wide pool per billing cycle. Each call draws from the organization’s included allowance first, then from the pack pool, then from overage at $0.03 per minute. Packs cover inbound, outbound, and Voice AI calls. Unused pack minutes expire when your plan renews. This endpoint requires an organization admin session or an admin-scoped API key.

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Request body

quantity sets the total, not a delta, so retrying the same request is safe.
  • Increase: Inkbox invoices the added packs immediately, prorated to the rest of the cycle, and adds their full minutes to the pool right away.
  • Decrease: The removed packs stop renewing. You keep this cycle’s minutes, and Inkbox issues no credit.
This example sets the organization to two 250-minute packs:
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Response (200)

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Errors

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Manage packs in the Console

Admins can also buy and remove packs in the Additional call minutes panel on the Billing tab of the Inkbox Console. The Billing tab also shows a Your subscription summary. The Usage tab shows pack usage in the Minute packs stat.

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Read billing settings

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Response (200)

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Update billing settings

Omitted fields stay unchanged. The response returns both current settings. This example sets a $25 overage limit:
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When estimated overage spending reaches the limit, new sends and calls that would incur overage return 402 until the cycle resets or you raise the limit. Included usage remains available. Inbound and in-progress usage can exceed the limit, so this setting is not a strict invoice ceiling. Setting remove_branding_footer to true on the Free plan returns 403. The footer always appears on Free, even if you enabled its removal while on a paid plan. Custom email signatures are a separate paid-plan feature. Set signature_enabled on an individual mailbox to control its custom signature. Set remove_branding_footer here to control the organization’s Sent via Inkbox footer. Neither setting changes the other. When both appear, the custom signature comes first.