# Grow RCS subscribers with a sign-up form
Once you have the phone number of an Android device user, you'll be able to communicate with them via RCS by sending [campaigns](https://docs.bird.com/applications/campaigns) or [journeys](https://docs.bird.com/applications/channels/channels/supported-channels/google-rcs/broken-reference).
[Sign-up forms](https://docs.bird.com/applications/sign-up-forms/overview) are an easy way to collect phone numbers from people who sign up to your website.
By adding a phone number collection step to your sign-up forms, you can easily and quickly grow your subscribers.
{% hint style="info" %}
For in-depth information on sign-up forms, visit the [sign-up form](https://docs.bird.com/applications/sign-up-forms/overview) section of the docs.
{% endhint %}
## How to build a sign-up form to collect subscribers
Sign up forms can be completely customized to match your branding and website, and you can add images too to entice your customers.
Because we're building a sign-up form to collect phone numbers so that we can send RCS campaigns and/or journeys, you'll need to make sure you add a phone number block to your sign up form as you build it.
#### What you'll need
* An [RCS Agent](https://docs.bird.com/applications/channels/channels/supported-channels/google-rcs/create-a-google-rcs-agent-and-install-google-rcs-as-a-channel) and [RCS installed as a channel](https://docs.bird.com/applications/channels/channels/supported-channels/create-a-google-rcs-agent-and-install-google-rcs-as-a-channel#step-4-install-rcs-as-a-channel)
### Step 1: Create a list
The first thing you need to do is create a list. Once your sign-up form is live, every contact that submits the sign-up form will be added to this list. You can then use this list to send [campaigns](https://docs.bird.com/applications/campaigns) or trigger [journeys](https://docs.bird.com/applications/channels/channels/supported-channels/google-rcs/broken-reference).
### Step 2: Build your sign up form
The next step is to build your sign-up form.
1. From the **Marketing** section of your workspace, go to **Sign-up forms** > **Create new sign-up form**.
2. Name your sign-up form and choose your default language.
3. Under 'Which list should subscribers be added to?', select the list you created in Step 1 from the drop-down.
4. Choose if you want to install your sign-up form on an e-commerce store or on a website, then click **Create sign-up form**.
5. In the **Overview** panel on the left-hand side of your screen, click **Content**.
6. Click **Add new block**, and select **Phone**.\
7. Under 'Contact opt-in', select your RCS channel from the drop-down.
8. Use the settings in the panel to design the phone number block, then click the ← button to return to the form settings.
9. Continue to customize and style the rest of your sign-up form.
10. When ready, **Publish** and/or embed your form.
### What next?
#### Send a campaign
As users submit your sign-up form, they'll automatically be added to the list you selected during the set-up process. You can use this list to send a one-off RCS marketing campaign to that list.
{% content-ref url="../../../../campaigns/campaigns/quickstarts/send-a-campaign" %}
[send-a-campaign](https://docs.bird.com/applications/campaigns/campaigns/quickstarts/send-a-campaign)
{% endcontent-ref %}
#### Trigger a journey
You can set up a journey to run automatically when a contact is added to the list that is connected to the sign-up form.
