---
id: KB-CC-002
url: https://app.codecontract.io/help/contacts-and-channels/which-channel-for-which-message
idioma: en
categoria: contactos-canales
audiencia: usuario
nivel: intermedio
actualizado: 2026-08-13
tambienEn: [es]
relacionados: [KB-CC-001, KB-PR-003, KB-CC-017]
citadoPor: [KB-CC-003, KB-TD-002, KB-TD-009, KB-CC-011, KB-CC-013, KB-CC-016, KB-CC-019, KB-CC-009, KB-CC-004, KB-CC-006, KB-CC-007]
---

# Which channel for which message

_Email, SMS or WhatsApp: which arrives, which annoys, and which costs._

**Responde a:** best channel to request documents · when to use whatsapp instead of email · send notices by sms · the client does not read emails

The same message performs differently depending on the route. It is not a matter of taste: each channel has a place where it is read and a threshold for what counts as intrusive.

| Channel | Read | Cost | Good for |
| --- | --- | --- | --- |
| Email | When the inbox is opened | Same as the others | Anything with documents that needs reading properly |
| SMS | Almost immediately | Same | Urgent things, and reaching people who do not use email |
| WhatsApp | Immediately | Same | Third parties you already talk to there |

## The practical rule

- Start with email: it costs the same as any other channel and carries detail.
- Escalate to SMS when email did not arrive or there is genuine urgency.
- Use WhatsApp only if you already have that relationship; otherwise it reads as intrusion.

> [!WARNING]
> Sending the same notice on all three channels at once does not triple delivery: it reads as harassment, and the first time you do it you will earn a block.

## When to switch channel

If the notice was opened and there is still no reply, switching channel adds nothing: the message arrived. Switching helps when the previous one did not arrive — a bounced email, or three unopened notices.

> [!NOTE]
> For people working on site or on the road, email arrives late and a phone always arrives. There, SMS is not chasing: it is the right channel from the start.

**Can I choose the channel per contact?**

Yes, and it is worth it for the ones you know do not read email.

**What if I do not have their mobile?**

Only email remains. Asking for the mobile when creating the contact saves weeks later.

**Does WhatsApp have to be a business number?**

Yes, a verified one. A personal number inspires no confidence and cannot be audited.

## Ejemplos

**A construction firm cannot get paperwork from site managers who never open email.**

- Sets SMS as the preferred channel for that group

→ Delivery goes from days to hours, because the notice lands where that person actually looks.

**An urgent notice goes by email and is read the next day.**

- Uses a more immediate channel for what is urgent

→ The urgency arrives in time.

**A long link is sent by message and gets truncated.**

- Sends the link on a channel that preserves it

→ The link arrives whole.

**Sensitive documentation goes out on any channel.**

- Uses the channel that matches the content

→ Sensitive material travels where it should.

**Channels are combined and the recipient gets three notices.**

- Defines one channel per notice type

→ Nobody receives the same thing three times.

**The channel is chosen without knowing what the recipient uses.**

- Asks or records their preference

→ The first send already works.