Phone-number identity for agents

Most agent frameworks treat phone numbers as ephemeral — claim one, use it for verification, throw it away. That's correct for one-off signups but wrong for any agent that needs to come back to the same account next week. SIMRelay supports durable per-agent phone identity: a number that belongs to a specific agent for as long as that agent needs it.

Why durable identity matters

If your agent signs up for a service with a number it later abandons, the next time the service triggers a phone-based recovery — password reset, suspicious-login challenge, regulatory step-up — the verification code arrives at a number you no longer hold. The account is locked, the agent has to re-onboard, and the workflow breaks. Durable numbers solve this.

Per-agent number assignment

Use the SIMRelay API to allocate a number, tag it with the agent's identifier (your own ID schema — we don't impose one), and lock it. From that point forward, every SMS arriving on that number is associated with that agent in your event logs, and your agent can poll or subscribe specifically to its own number's inbox.

Recycling policies

You decide when a number can be released. Common patterns:

• Permanent: kept for the agent's lifetime. Highest cost, lowest friction.
• Per-project: kept while the agent is actively working on a multi-day task, released afterward.
• Per-account-relationship: kept as long as the agent has an active account on the service it signed up for.

When a number is released, it goes through SIMRelay's cooldown before re-entering the pool — long enough that the next holder won't receive stray messages from the previous account.

Audit trail

Every claim, lock, release, and inbound SMS on a number is recorded with timestamps and the actor (your API key or agent identifier). When something goes wrong — and in agent workflows, eventually something does — you can reconstruct exactly which message went where.