diff --git a/compiler/noirc_driver/src/abi_gen.rs b/compiler/noirc_driver/src/abi_gen.rs
index d0b33945f40..6625eba5a0a 100644
--- a/compiler/noirc_driver/src/abi_gen.rs
+++ b/compiler/noirc_driver/src/abi_gen.rs
@@ -116,7 +116,7 @@ fn to_abi_visibility(value: Visibility) -> AbiVisibility {
     match value {
         Visibility::Public => AbiVisibility::Public,
         Visibility::Private => AbiVisibility::Private,
-        Visibility::DataBus => AbiVisibility::DataBus,
+        Visibility::CallData(_) | Visibility::ReturnData => AbiVisibility::DataBus,
     }
 }
 
diff --git a/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs b/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs
index dc0e026b3d1..d7dd5e5dbce 100644
--- a/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs
+++ b/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs
@@ -430,6 +430,12 @@ impl<'a> Context<'a> {
         let (return_vars, return_warnings) =
             self.convert_ssa_return(entry_block.unwrap_terminator(), dfg)?;
 
+        let call_data_arrays: Vec<ValueId> =
+            self.data_bus.call_data.iter().map(|cd| cd.array_id).collect();
+        for call_data_array in call_data_arrays {
+            self.ensure_array_is_initialized(call_data_array, dfg)?;
+        }
+
         // TODO: This is a naive method of assigning the return values to their witnesses as
         // we're likely to get a number of constraints which are asserting one witness to be equal to another.
         //
@@ -1263,20 +1269,23 @@ impl<'a> Context<'a> {
         let res_typ = dfg.type_of_value(results[0]);
 
         // Get operations to call-data parameters are replaced by a get to the call-data-bus array
-        if let Some(call_data) = self.data_bus.call_data {
-            if self.data_bus.call_data_map.contains_key(&array) {
-                // TODO: the block_id of call-data must be notified to the backend
-                // TODO: should we do the same for return-data?
-                let type_size = res_typ.flattened_size();
-                let type_size =
-                    self.acir_context.add_constant(FieldElement::from(type_size as i128));
-                let offset = self.acir_context.mul_var(var_index, type_size)?;
-                let bus_index = self
-                    .acir_context
-                    .add_constant(FieldElement::from(self.data_bus.call_data_map[&array] as i128));
-                let new_index = self.acir_context.add_var(offset, bus_index)?;
-                return self.array_get(instruction, call_data, new_index, dfg, index_side_effect);
-            }
+        if let Some(call_data) =
+            self.data_bus.call_data.iter().find(|cd| cd.index_map.contains_key(&array))
+        {
+            let type_size = res_typ.flattened_size();
+            let type_size = self.acir_context.add_constant(FieldElement::from(type_size as i128));
+            let offset = self.acir_context.mul_var(var_index, type_size)?;
+            let bus_index = self
+                .acir_context
+                .add_constant(FieldElement::from(call_data.index_map[&array] as i128));
+            let new_index = self.acir_context.add_var(offset, bus_index)?;
+            return self.array_get(
+                instruction,
+                call_data.array_id,
+                new_index,
+                dfg,
+                index_side_effect,
+            );
         }
 
         // Compiler sanity check
@@ -1707,17 +1716,20 @@ impl<'a> Context<'a> {
         len: usize,
         value: Option<AcirValue>,
     ) -> Result<(), InternalError> {
-        let databus = if self.data_bus.call_data.is_some()
-            && self.block_id(&self.data_bus.call_data.unwrap()) == array
-        {
-            BlockType::CallData
-        } else if self.data_bus.return_data.is_some()
+        let mut databus = BlockType::Memory;
+        if self.data_bus.return_data.is_some()
             && self.block_id(&self.data_bus.return_data.unwrap()) == array
         {
-            BlockType::ReturnData
-        } else {
-            BlockType::Memory
-        };
+            databus = BlockType::ReturnData;
+        }
+        for array_id in self.data_bus.call_data_array() {
+            if self.block_id(&array_id) == array {
+                assert!(databus == BlockType::Memory);
+                databus = BlockType::CallData;
+                break;
+            }
+        }
+
         self.acir_context.initialize_array(array, len, value, databus)?;
         self.initialized_arrays.insert(array);
         Ok(())
diff --git a/compiler/noirc_evaluator/src/ssa/function_builder/data_bus.rs b/compiler/noirc_evaluator/src/ssa/function_builder/data_bus.rs
index 5f0660f5a79..50964e9161b 100644
--- a/compiler/noirc_evaluator/src/ssa/function_builder/data_bus.rs
+++ b/compiler/noirc_evaluator/src/ssa/function_builder/data_bus.rs
@@ -1,3 +1,4 @@
+use std::collections::BTreeMap;
 use std::rc::Rc;
 
 use crate::ssa::ir::{types::Type, value::ValueId};
@@ -8,6 +9,12 @@ use noirc_frontend::hir_def::function::FunctionSignature;
 
 use super::FunctionBuilder;
 
+#[derive(Clone)]
+pub(crate) enum DatabusVisibility {
+    None,
+    CallData(u32),
+    ReturnData,
+}
 /// Used to create a data bus, which is an array of private inputs
 /// replacing public inputs
 pub(crate) struct DataBusBuilder {
@@ -27,15 +34,16 @@ impl DataBusBuilder {
         }
     }
 
-    /// Generates a boolean vector telling which (ssa) parameter from the given function signature
+    /// Generates a vector telling which (ssa) parameters from the given function signature
     /// are tagged with databus visibility
-    pub(crate) fn is_databus(main_signature: &FunctionSignature) -> Vec<bool> {
+    pub(crate) fn is_databus(main_signature: &FunctionSignature) -> Vec<DatabusVisibility> {
         let mut params_is_databus = Vec::new();
 
         for param in &main_signature.0 {
             let is_databus = match param.2 {
-                ast::Visibility::Public | ast::Visibility::Private => false,
-                ast::Visibility::DataBus => true,
+                ast::Visibility::Public | ast::Visibility::Private => DatabusVisibility::None,
+                ast::Visibility::CallData(id) => DatabusVisibility::CallData(id),
+                ast::Visibility::ReturnData => DatabusVisibility::ReturnData,
             };
             let len = param.1.field_count() as usize;
             params_is_databus.extend(vec![is_databus; len]);
@@ -44,34 +52,51 @@ impl DataBusBuilder {
     }
 }
 
+#[derive(Clone, Debug)]
+pub(crate) struct CallData {
+    pub(crate) array_id: ValueId,
+    pub(crate) index_map: HashMap<ValueId, usize>,
+}
+
 #[derive(Clone, Default, Debug)]
 pub(crate) struct DataBus {
-    pub(crate) call_data: Option<ValueId>,
-    pub(crate) call_data_map: HashMap<ValueId, usize>,
+    pub(crate) call_data: Vec<CallData>,
     pub(crate) return_data: Option<ValueId>,
 }
 
 impl DataBus {
     /// Updates the databus values with the provided function
     pub(crate) fn map_values(&self, mut f: impl FnMut(ValueId) -> ValueId) -> DataBus {
-        let mut call_data_map = HashMap::default();
-        for (k, v) in self.call_data_map.iter() {
-            call_data_map.insert(f(*k), *v);
-        }
-        DataBus {
-            call_data: self.call_data.map(&mut f),
-            call_data_map,
-            return_data: self.return_data.map(&mut f),
-        }
+        let call_data = self
+            .call_data
+            .iter()
+            .map(|cd| {
+                let mut call_data_map = HashMap::default();
+                for (k, v) in cd.index_map.iter() {
+                    call_data_map.insert(f(*k), *v);
+                }
+                CallData { array_id: f(cd.array_id), index_map: call_data_map }
+            })
+            .collect();
+        DataBus { call_data, return_data: self.return_data.map(&mut f) }
     }
 
+    pub(crate) fn call_data_array(&self) -> Vec<ValueId> {
+        self.call_data.iter().map(|cd| cd.array_id).collect()
+    }
     /// Construct a databus from call_data and return_data data bus builders
-    pub(crate) fn get_data_bus(call_data: DataBusBuilder, return_data: DataBusBuilder) -> DataBus {
-        DataBus {
-            call_data: call_data.databus,
-            call_data_map: call_data.map,
-            return_data: return_data.databus,
+    pub(crate) fn get_data_bus(
+        call_data: Vec<DataBusBuilder>,
+        return_data: DataBusBuilder,
+    ) -> DataBus {
+        let mut call_data_args = Vec::new();
+        for call_data_item in call_data {
+            if let Some(array_id) = call_data_item.databus {
+                call_data_args.push(CallData { array_id, index_map: call_data_item.map });
+            }
         }
+
+        DataBus { call_data: call_data_args, return_data: return_data.databus }
     }
 }
 
@@ -129,19 +154,36 @@ impl FunctionBuilder {
     }
 
     /// Generate the data bus for call-data, based on the parameters of the entry block
-    /// and a boolean vector telling which ones are call-data
-    pub(crate) fn call_data_bus(&mut self, is_params_databus: Vec<bool>) -> DataBusBuilder {
+    /// and a vector telling which ones are call-data
+    pub(crate) fn call_data_bus(
+        &mut self,
+        is_params_databus: Vec<DatabusVisibility>,
+    ) -> Vec<DataBusBuilder> {
         //filter parameters of the first block that have call-data visibility
         let first_block = self.current_function.entry_block();
         let params = self.current_function.dfg[first_block].parameters();
-        let mut databus_param = Vec::new();
-        for (param, is_databus) in params.iter().zip(is_params_databus) {
-            if is_databus {
-                databus_param.push(param.to_owned());
+        let mut databus_param: BTreeMap<u32, Vec<ValueId>> = BTreeMap::new();
+        for (param, databus_attribute) in params.iter().zip(is_params_databus) {
+            match databus_attribute {
+                DatabusVisibility::None | DatabusVisibility::ReturnData => continue,
+                DatabusVisibility::CallData(call_data_id) => {
+                    if let std::collections::btree_map::Entry::Vacant(e) =
+                        databus_param.entry(call_data_id)
+                    {
+                        e.insert(vec![param.to_owned()]);
+                    } else {
+                        databus_param.get_mut(&call_data_id).unwrap().push(param.to_owned());
+                    }
+                }
             }
         }
-        // create the call-data-bus from the filtered list
-        let call_data = DataBusBuilder::new();
-        self.initialize_data_bus(&databus_param, call_data)
+        // create the call-data-bus from the filtered lists
+        let mut result = Vec::new();
+        for id in databus_param.keys() {
+            let builder = DataBusBuilder::new();
+            let call_databus = self.initialize_data_bus(&databus_param[id], builder);
+            result.push(call_databus);
+        }
+        result
     }
 }
diff --git a/compiler/noirc_evaluator/src/ssa/opt/die.rs b/compiler/noirc_evaluator/src/ssa/opt/die.rs
index 42383680f44..24519d530ee 100644
--- a/compiler/noirc_evaluator/src/ssa/opt/die.rs
+++ b/compiler/noirc_evaluator/src/ssa/opt/die.rs
@@ -34,8 +34,8 @@ impl Ssa {
 /// of its instructions are needed elsewhere.
 fn dead_instruction_elimination(function: &mut Function) {
     let mut context = Context::default();
-    if let Some(call_data) = function.dfg.data_bus.call_data {
-        context.mark_used_instruction_results(&function.dfg, call_data);
+    for call_data in &function.dfg.data_bus.call_data {
+        context.mark_used_instruction_results(&function.dfg, call_data.array_id);
     }
 
     let blocks = PostOrder::with_function(function);
diff --git a/compiler/noirc_evaluator/src/ssa/ssa_gen/mod.rs b/compiler/noirc_evaluator/src/ssa/ssa_gen/mod.rs
index abd251b008f..468a8573307 100644
--- a/compiler/noirc_evaluator/src/ssa/ssa_gen/mod.rs
+++ b/compiler/noirc_evaluator/src/ssa/ssa_gen/mod.rs
@@ -44,7 +44,7 @@ pub(crate) fn generate_ssa(
     // see which parameter has call_data/return_data attribute
     let is_databus = DataBusBuilder::is_databus(&program.main_function_signature);
 
-    let is_return_data = matches!(program.return_visibility, Visibility::DataBus);
+    let is_return_data = matches!(program.return_visibility, Visibility::ReturnData);
 
     let return_location = program.return_location;
     let context = SharedContext::new(program);
diff --git a/compiler/noirc_frontend/src/ast/mod.rs b/compiler/noirc_frontend/src/ast/mod.rs
index 038a13529d7..b97853033a8 100644
--- a/compiler/noirc_frontend/src/ast/mod.rs
+++ b/compiler/noirc_frontend/src/ast/mod.rs
@@ -390,7 +390,9 @@ pub enum Visibility {
     Private,
     /// DataBus is public input handled as private input. We use the fact that return values are properly computed by the program to avoid having them as public inputs
     /// it is useful for recursion and is handled by the proving system.
-    DataBus,
+    /// The u32 value is used to group inputs having the same value.
+    CallData(u32),
+    ReturnData,
 }
 
 impl std::fmt::Display for Visibility {
@@ -398,7 +400,8 @@ impl std::fmt::Display for Visibility {
         match self {
             Self::Public => write!(f, "pub"),
             Self::Private => write!(f, "priv"),
-            Self::DataBus => write!(f, "databus"),
+            Self::CallData(id) => write!(f, "calldata{id}"),
+            Self::ReturnData => write!(f, "returndata"),
         }
     }
 }
diff --git a/compiler/noirc_frontend/src/parser/errors.rs b/compiler/noirc_frontend/src/parser/errors.rs
index c566489eb40..80adb01dc9a 100644
--- a/compiler/noirc_frontend/src/parser/errors.rs
+++ b/compiler/noirc_frontend/src/parser/errors.rs
@@ -46,6 +46,8 @@ pub enum ParserErrorReason {
     Lexer(LexerErrorKind),
     #[error("The only supported numeric generic types are `u1`, `u8`, `u16`, and `u32`")]
     ForbiddenNumericGenericType,
+    #[error("Invalid call data identifier, must be a number. E.g `call_data(0)`")]
+    InvalidCallDataIdentifier,
 }
 
 /// Represents a parsing error, or a parsing error in the making.
diff --git a/compiler/noirc_frontend/src/parser/parser.rs b/compiler/noirc_frontend/src/parser/parser.rs
index 3879f628eae..46d0ca5d206 100644
--- a/compiler/noirc_frontend/src/parser/parser.rs
+++ b/compiler/noirc_frontend/src/parser/parser.rs
@@ -46,6 +46,7 @@ use crate::ast::{
 use crate::lexer::{lexer::from_spanned_token_result, Lexer};
 use crate::parser::{force, ignore_then_commit, statement_recovery};
 use crate::token::{Keyword, Token, TokenKind};
+use acvm::AcirField;
 
 use chumsky::prelude::*;
 use iter_extended::vecmap;
@@ -645,19 +646,28 @@ where
     })
 }
 
+fn call_data() -> impl NoirParser<Visibility> {
+    keyword(Keyword::CallData).then(parenthesized(literal())).validate(|token, span, emit| {
+        match token {
+            (_, ExpressionKind::Literal(Literal::Integer(x, _))) => {
+                let id = x.to_u128() as u32;
+                Visibility::CallData(id)
+            }
+            _ => {
+                emit(ParserError::with_reason(ParserErrorReason::InvalidCallDataIdentifier, span));
+                Visibility::CallData(0)
+            }
+        }
+    })
+}
+
 fn optional_visibility() -> impl NoirParser<Visibility> {
     keyword(Keyword::Pub)
-        .or(keyword(Keyword::CallData))
-        .or(keyword(Keyword::ReturnData))
+        .map(|_| Visibility::Public)
+        .or(call_data())
+        .or(keyword(Keyword::ReturnData).map(|_| Visibility::ReturnData))
         .or_not()
-        .map(|opt| match opt {
-            Some(Token::Keyword(Keyword::Pub)) => Visibility::Public,
-            Some(Token::Keyword(Keyword::CallData)) | Some(Token::Keyword(Keyword::ReturnData)) => {
-                Visibility::DataBus
-            }
-            None => Visibility::Private,
-            _ => unreachable!("unexpected token found"),
-        })
+        .map(|opt| opt.unwrap_or(Visibility::Private))
 }
 
 pub fn expression() -> impl ExprParser {
diff --git a/test_programs/execution_success/databus/src/main.nr b/test_programs/execution_success/databus/src/main.nr
index 7e5c23d508d..1e4aa141eea 100644
--- a/test_programs/execution_success/databus/src/main.nr
+++ b/test_programs/execution_success/databus/src/main.nr
@@ -1,4 +1,4 @@
-fn main(mut x: u32, y: call_data u32, z: call_data [u32; 4]) -> return_data u32 {
+fn main(mut x: u32, y: call_data(0) u32, z: call_data(0) [u32; 4]) -> return_data u32 {
     let a = z[x];
     a + foo(y)
 }
diff --git a/tooling/nargo_fmt/src/utils.rs b/tooling/nargo_fmt/src/utils.rs
index 020f411ae2f..293351055e1 100644
--- a/tooling/nargo_fmt/src/utils.rs
+++ b/tooling/nargo_fmt/src/utils.rs
@@ -146,9 +146,10 @@ impl HasItem for Param {
     fn format(self, visitor: &FmtVisitor, shape: Shape) -> String {
         let pattern = visitor.slice(self.pattern.span());
         let visibility = match self.visibility {
-            Visibility::Public => "pub",
-            Visibility::Private => "",
-            Visibility::DataBus => "call_data",
+            Visibility::Public => "pub".to_string(),
+            Visibility::Private => "".to_string(),
+            Visibility::CallData(x) => format!("call_data({x})"),
+            Visibility::ReturnData => "return_data".to_string(),
         };
 
         if self.pattern.is_synthesized() || self.typ.is_synthesized() {
diff --git a/tooling/nargo_fmt/src/visitor/item.rs b/tooling/nargo_fmt/src/visitor/item.rs
index 5aaaf20ff47..0c9f61a7d40 100644
--- a/tooling/nargo_fmt/src/visitor/item.rs
+++ b/tooling/nargo_fmt/src/visitor/item.rs
@@ -120,8 +120,11 @@ impl super::FmtVisitor<'_> {
 
             let visibility = match func.def.return_visibility {
                 Visibility::Public => "pub",
-                Visibility::DataBus => "return_data",
+                Visibility::ReturnData => "return_data",
                 Visibility::Private => "",
+                Visibility::CallData(_) => {
+                    unreachable!("call_data cannot be used for return value")
+                }
             };
             result.push_str(&append_space_if_nonempty(visibility.into()));