AWS End User Messaging — SMS, Voice, RCS & Notify

Overview

AWS End User Messaging SMS and Voice (the pinpoint-sms-voice-v2 API) is the control and data plane for SMS, Voice, RCS Business Messaging, and Notify (OTP). This skill covers the two fastest onboarding paths — each reaches a real message on a real phone in about five minutes, with no phone-number purchase and no carrier registration:

1. Create an RCS test agent and send your first branded message — a branded RCS Business Messaging agent, a verified test device, and a rich outbound + inbound message. See references/hello-rcs-test-agent.md.
2. Send an OTP with Notify — a one-time-passcode text through AWS-managed sending identities and pre-approved templates. See references/hello-notify-otp.md.

Beyond onboarding, this skill takes an identity to production registration in three steps:

1. Find which registration a country requires — discover the registration type and its live field set for a target country and identity type, reconciled with the official docs. See references/registration-requirements-by-country.md.
2. Run the registration lifecycle — the universal engine (create, derive fields, fill, submit, poll, recover from denial, resubmit) shared by every registration type, including RCS country launch. See references/registration-core-engine.md.
3. Take an identity to production — exit the SMS sandbox, launch RCS in a country with carrier monitoring and SMS fallback, upgrade Notify to Advanced, and apply production hygiene (keywords, configuration sets, protect configurations). See references/customer-go-to-production-guide.md.

Guardrail — where this skill's files live (MCP vs local install)

This skill can be loaded two ways, and the references/ files resolve differently:

• Loaded through the AWS MCP retrieve_skill tool. Reference files do not exist on the local filesystem. Fetch them via retrieve_skill with the file parameter (e.g., file="references/hello-rcs-test-agent.md"). Do NOT file_read these paths locally — they are not there.
• Installed locally (e.g., .kiro/skills/aws-sms-voice/). Read references from the local skill directory using the relative paths shown in this file.

This applies only to the skill's own packaged files. User-created artifacts (brand-assets/, temp files) are always in the user's working directory.

Execute commands using available tools from the AWS MCP server when connected — it provides sandboxed execution, audit logging, and observability. When the MCP server is not available, fall back to the AWS CLI or shell as needed.

Choosing a path

RCS test agents deliver only to verified test devices and require a short brand registration (auto-reviewed in minutes). Notify sends to any recipient in its supported countries immediately, but is limited to AWS-managed OTP templates. Pick RCS to explore rich messaging; pick Notify for the shortest path to a production-grade verification text.

Before you start (both paths)

The AWS MCP server is recommended for the best experience here — it runs the many pinpoint-sms-voice-v2 and sts calls with sandboxed execution, audit logging, and observability. It is not a hard requirement: every step also works with the plain AWS CLI or the AWS Agent Toolkit when the MCP server is not available.

1. Credentials. Run aws sts get-caller-identity --region <REGION> (pass --region to use the regional STS endpoint; the global sts.amazonaws.com endpoint is legacy). If it fails, configure the user's auth (named profile / SSO / access keys — --profile <PROFILE> on every command if a profile is in play) and prefer an assumed IAM role with ephemeral credentials. Each reference file's Prerequisites carry the full auth, CloudTrail-audit, and CLI-freshness steps.
2. Least-privilege access. These tasks need a small set of specific sms-voice: actions in the target account (the reference files enumerate the read/write actions each step uses — for example sms-voice:DescribeRcsAgents, CreateRcsAgent, CreateRegistration, CreateNotifyConfiguration, and SendNotifyTextMessage). Scope the policy to exactly the actions the chosen path uses; do not grant sms-voice:* or *FullAccess.
3. Don't trust the CLI version. Treat any Invalid choice '<operation>' on a pinpoint-sms-voice-v2 command, at any step, as a stale/partial local service model (not a permissions or account problem). The RCS and Notify reference files (prerequisite 3) carry the full reactive resolution: clear a stale ~/.aws/models/pinpoint-sms-voice-v2/ override, else upgrade the AWS CLI, with a boto3 fallback. AccessDeniedException means the identity is missing the required sms-voice: permissions.

Each reference file is self-contained: it tracks the IDs you collect as session state, audits required inputs against the service before any submit, and ends with a Failure modes table and a Cleanup section. Follow the file for the path the user chose rather than improvising the API sequence — several steps fail silently or depend on service-version-specific field sets that must be read live.

Security Considerations

• Least-privilege IAM. Scope policies to specific sms-voice: actions; never use *FullAccess or sms-voice:* in production. The reference files enumerate the minimal read/write actions each onboarding path needs.
• Ephemeral credentials. Assume an IAM role with ephemeral credentials; never embed long-lived access keys in code, config, or environment variables.
• No secrets in messages or fields. OTP codes and message bodies can surface in CloudTrail and downstream logs — treat them as sensitive and never hardcode real codes. Enable CloudTrail logging for sms-voice API calls and encrypt CloudTrail logs and CloudWatch Log groups with a KMS CMK. Attach a configuration set with an event destination (CloudWatch Logs or Kinesis) for delivery monitoring before production traffic. Create CloudWatch alarms on key security signals (repeated AccessDeniedException, unusual send volumes, spend limit approaching threshold) for proactive alerting. Registration contact fields (email, phone, URLs) are submitted to partner review; use real but non-sensitive business contacts.
• Consent and opt-out. Only message recipients who have opted in. Honor STOP / opt-out state; the RCS path shows how to check the opt-out list before sending. Test agents intentionally restrict delivery to verified test devices — do not work around that to reach unconsented numbers.
• Spend limits and abuse. Default account spend limits are intentionally low; raise them deliberately and monitor. Notify enforces a non-adjustable per-day cap per destination — do not attempt to bypass it.
• Destructive cleanup. The teardown steps delete agents, registrations, and configurations. They are irreversible — confirm with the user before running cleanup, and note RCS agents have deletion protection enabled by default in the onboarding flow.

Additional Resources

• AWS End User Messaging SMS User Guide
• AWS CLI pinpoint-sms-voice-v2 Reference
• RCS messaging on AWS End User Messaging
• AWS End User Messaging Notify
• IAM Security Best Practices