Message Filters (Regex)

Message filters let you control which incoming messages get forwarded to your destinations. This is an advanced feature that most users don't need, but it can be very useful if your Syfon number receives messages you don't want forwarded.

How filters work

Filters use regex (regular expressions) – a way to pattern match text and characters. Examples are shown on this page, and you can learn more about regex here.

When you add a filter to a flow, Syfon checks every incoming message against your filter pattern before forwarding it.

• If the message matches the filter, it gets forwarded to all your destinations as normal.
• If the message does not match, it gets stored in your message history but is not forwarded anywhere.

This means you'll always have a record of every message, but only the ones you care about will reach your team.

When to use a filter

Filters are useful when:

• Your Syfon number gets spam or marketing texts, and you only want to forward the important ones.
• You only care about messages that contain certain words, like "verification" or "code."
• You want to forward messages from specific senders or containing specific patterns.

If you want every message forwarded (which is the most common setup), you don't need a filter at all.

Adding a filter

1. Go to the flow detail page (click on any flow from the Flows page).
2. Find the Regex Filter field in the flow details section.
3. Click on it to start editing.
4. Type your filter pattern.
5. Click Save.

Writing filter patterns

Filters use "regular expressions" (regex), which are a way to describe text patterns. Here are some common examples:

Forward messages containing a specific word

To only forward messages that contain the word "code":

code

This matches any message with "code" anywhere in it, like "Your verification code is 1234" or "Enter this code to log in."

Forward messages containing any of several words

To forward messages that contain "code" or "verify" or "OTP":

code|verify|OTP

The | symbol means "or."

Forward messages with a number pattern

To only forward messages that contain a 6-digit number (like a verification code):

\d{6}

\d means "any digit" and {6} means "exactly 6 in a row." This would match "Your code is 482910" but not "Call us at 555-1234" (because the digits aren't all together).

Forward messages that start with certain text

To only forward messages that start with "Your verification":

^Your verification

The ^ symbol means "starts with."

Ignore case

Regular expressions are case-sensitive by default. To match regardless of uppercase or lowercase, use:

(?i)code

The (?i) at the beginning makes the whole pattern case-insensitive, so this matches "Code," "CODE," and "code."

Common filter examples

What you want	Filter pattern	What it matches
Messages with "verification"	verification	"Your verification code is 1234"
Messages with "code" or "OTP"	code|OTP	"Your code is 1234" or "OTP: 5678"
Messages with a 4-6 digit number	\d{4,6}	"Code: 1234" or "Your OTP: 482910"
Messages starting with "Your"	^Your	"Your code is..." but not "Enter your code"
Any message (no filter needed)	Leave empty	Everything gets forwarded

Removing a filter

1. Go to the flow detail page.
2. Click on the filter pattern field.
3. Clear the text so it's empty.
4. Click Save.

With no filter set, every incoming message will be forwarded.

Tips

• Start simple. A single word like code is often enough.
• Test your filter. After adding a filter, send a test message to your Syfon number and check if it gets forwarded.
• Check your message history. Filtered-out messages still show up in your Messages page, so you can see what's being caught by the filter.
• Filters have a maximum length of 200 characters.