Saperly gives AI agents real phone numbers for voice calls and SMS. Provision and manage numbers, place outbound calls, handle inbound conversations, send and receive text messages, configure voice agents, verify consent, and monitor usage and call
ChatGPT is OpenAI's assistant. It can add custom MCP servers as plugins, which lets it call your tools from a conversation.
This guide connects Saperly MCP to ChatGPT through MewCP, so ChatGPT can use Saperly MCP's 24 tools, like list_numbers, get_number and search_available_numbers, without your Saperly MCP credentials ever reaching the app.
Your Saperly MCP API key is stored encrypted and injected only at call time. Your agent never holds it, so it can never leak it, log it or paste it into a prompt.
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Saperly MCP works the same way in every client below. Pick yours for its own guide.
Free to start.
Scope access to the exact Saperly MCP tools and accounts you allow, work and personal side by side. Anything outside that scope is refused at call time, even when the model asks for it.
Each call is logged: what ran, on which account, and whether it worked. Failures come back structured, so the agent knows whether to retry instead of guessing.
Every app sits behind one secure MCP URL, and there is no server for you to deploy or keep running. Add an integration in the dashboard and it is live on the next call, with no config to change and no new credentials to wire up. Tools load only when a task needs them, so your agent stays fast and focused however many apps you connect.
In ChatGPT, open Plugins and choose Add custom MCP.
Name it "mewcp" and paste the server URL.
Click Connect. A sign-in window opens; sign in to MewCP and approve access. No API key needed.
Start a new chat and ask: "List the tools you can use from MewCP." You should see your connected apps.
List the active phone numbers (lines) provisioned in this workspace.
Fetch one phone number by its Saperly id.
Search available inventory for numbers available to provision, priced for this workspace.
Order a new phone number and add it to this workspace. Charges the prepaid balance. The first number needs no card; provisioning a SECOND number requires a saved payment method on file (otherwise it fails with PaymentMethodRequired).
Release a phone number and stop billing it.
Attach a connection (the handler that answers calls) to a number — i.e. configure the line.
Set (or clear) a line’s alphanumeric SMS sender name — the 1–11 letter/number label recipients see as the “from” on INTERNATIONAL SMS only. US & Canada carriers don’t allow alphanumeric senders, so US/Canada recipients always see the phone number. It is one-way (recipients can’t reply to a name). Pass an empty string or null to clear it (revert to sending from the phone number). A bad value returns InvalidSmsSenderId. Line-reconfiguration, so a number-scoped key is bounded to its allow-list.
Set (or clear) a line’s outbound CALLER ID NAME — the 1–15 letter/number/space display name (CNAM) shown alongside the number on the called party’s phone. Unlike the SMS sender name this is NOT free per-call text: it’s a listing registered to the number, so display is best-effort (the recipient’s carrier decides via a CNAM dip; mainly US & Canada, and it takes time to propagate — many mobile carriers may not show it). Pass an empty string or null to clear it (show the bare number). A bad value returns InvalidCallerIdName. Line-reconfiguration, so a number-scoped key is bounded to its allow-list.
List stock voices and ready private voices. Pass an id as voiceId to create_connection or update_connection. Upload recordings in the dashboard or POST /custom-voices (multipart); private voices are hosted-only.
List this workspace’s private voices and their processing status. Upload recordings through the dashboard or multipart POST /custom-voices. Only active voices can be selected.
List the connections (call/message handlers) configured in this workspace.
Fetch one connection by its Saperly id.
Create a connection. hosted = an in-network AI assistant; manual = your own brain via BYO-LLM.
Update a connection’s name, instructions, compliance/disclosure — or switch its mode between hosted (an in-network AI assistant) and manual (your own brain via BYO-LLM). A mode switch reconciles automatically.
Delete a connection.
Reconcile a connection — create/update its assistant and mint its manual-mode secret.
Dial an outbound call from one of your numbers. The connection answers it.
Fetch one call record by its Saperly id.
List the calls in this workspace.
Blind-transfer a live call to another destination — an E.164 phone number or a sip: URI. A Call Control action (signaling only): the carrier re-bridges the leg to the destination; Saperly never touches the audio (the no-media rule). Works across every backend — hosted, manual, and openai_realtime — because it acts on the call’s bound carrier leg. Returns CallStartFailed if the call has no live leg or the carrier transfer fails.
Speak a line into a live call. NOTE: out-of-band speech injection is not available — the carrier owns the in-network audio loop and only pulls the brain on a caller turn. In manual mode the agent speaks by REPLYING on its turn (the BYO-LLM / agent-as-channel path); Saperly never holds the media path.
Send an SMS from one of your numbers.
List SMS messages in this workspace, optionally filtered to one number.
Summarize calls, messages, and the current balance for this workspace.
