How to Add the HOAM eSIM App to ChatGPT

ChatGPT can read HOAM's live catalogue once it's connected: real prices for the countries on your itinerary, the carrier networks you'll actually roam onto, and a link to buy the plan you settled on.

It takes one address and no account.

The address

https://mcp.hoamesim.com/mcp/chatgpt

Add it in ChatGPT's connector settings, then start a new chat.

Note this is not the same address as the Claude one. Same catalogue, same prices, but the two are served separately so each assistant gets output shaped for how it presents things. Pasting the wrong one is the most common setup mistake — if a connector behaves oddly, check you used the /chatgpt address here.

And don't open it in a browser to test it. It isn't a web page: it answers ChatGPT, not a browser, so all you'll get is a bare error. Test it by asking ChatGPT a question once it's added.

Setting it up

Connector settings move around as ChatGPT changes, and which plans can add a custom connector is decided by OpenAI rather than by us. As of writing, look under Settings → Connectors (sometimes shown as Apps), then the option to add one by URL.

If there's no such option in your settings, your plan doesn't include custom connectors — nothing on our side will change that.

Once it's added, open a new chat. A conversation that was already running won't pick it up.

Confirm it's live

Ask for something only the catalogue knows:

"Ask HOAM what an eSIM costs for Thailand and Vietnam for three weeks."

You want to see it call out to HOAM and come back with the sizes available for that pair. An answer that arrives instantly, with no tool call, is ChatGPT working from memory — and that answer can name a size we don't sell.

What you get back

A pricing question returns an interactive plan card: every data size available for your selection, the price against each, the recommended size marked, and a Buy button that opens the HOAM checkout with that plan already chosen.

Coverage and help-centre questions come back as plain answers — there's no card, because there's nothing to pick.

Prompts that get the most out of it

Give it the whole itinerary at once.

"Bangkok, then Hanoi, then a week in Ho Chi Minh City. What HOAM eSIM covers all of it?"

Multi-country is the point. All of it prices as one plan on one eSIM rather than a separate purchase per border.

Ask before you commit to a region.

"Is it cheaper to get HOAM for Switzerland and Austria separately, or as a Europe bundle?"

Worth asking because the answer is usually the countries, not the bundle — the pricing rules explain why.

Check the network, not just the price.

"Which carriers would my HOAM eSIM use in Mexico?"

Useful if you'll be away from cities, where which network you land on genuinely matters.

Ask the awkward product questions.

"If I don't use all my HOAM data, what happens to it?"

Answered from HOAM's own help centre. If we haven't published an answer, you'll be told that rather than given a guess about some other provider's policy.

When it misbehaves

Answers instantly with a price and no tool call. It's guessing. Say "check with the HOAM connector" explicitly, or start a new chat.

Says it can't find the connector. Confirm the address ends in /mcp/chatgpt, and that you started a new conversation after adding it.

Priced one country when you named three. Re-state the full list in one message. It prices whatever selection it was given, and a selection built up across several turns can lose a destination.

Returns nothing for a place. We may not cover it. Ask for the full destination list.

What's the same in both assistants

The catalogue, the prices, and the rules behind them don't change between hosts. How a multi-destination price is calculated, why a pair sometimes offers fewer data sizes than one country alone, and what the connector deliberately cannot do are all in The HOAM eSIM MCP server.

Also use Claude? Adding the connector there →