# Create dynamic text strings in Play prompt blocks in Connect Customer
Use a [Play prompt](play.md) block to use an audio file to play as a greeting or message to callers. You can also use contact attributes to specify the greeting or message delivered to callers. To use the values of a contact attribute to personalize a message for a customer, include references to stored or external contact attributes in the text-to-speech message.
For example, if you retrieved the customer’s name from a Lambda function, and it returns values from your customer database for FirstName and LastName, you could use these attributes to say the customer’s name in the text-to-speech block by including text similar to the following:
+ Hello $.External.FirstName $.External.LastName, thank you for calling.
This message is shown in the following image of the text-to-speech box of the [Play prompt](play.md) block.
Alternatively, you could store the attributes returned from the Lambda function using a **Set contact attributes** block, and then reference the user-defined attribute created in the text-to-speech string.
If you are referencing a user-defined attribute that was previously set as a contact attribute in the flow using the API, you can reference the attribute using the $.Attributes.nameOfAttribute syntax.
For example, if the contact in question has attributes "FirstName" and "LastName" set previously, reference them as follows:
+ Hello $.Attributes.FirstName $.Attributes.LastName, thank you for calling.
## Resolution using backticks
You can also use backticks (`) to resolve keys dynamically. For example, suppose you retrieve a customer's name from a Lambda function that returns FirstName and LastName values from your customer database. If the customer's preference for which name to use is stored in $.Attributes.NameToPlay, you can dynamically select the appropriate name by enclosing the dynamic key in backticks (`).
+ Hello $.External.['`$.Attributes.NameToPlay`'], thank you for calling.