diff --git a/BankingClient/src/commonMain/kotlin/net/codinux/banking/client/BankingClientCallback.kt b/BankingClient/src/commonMain/kotlin/net/codinux/banking/client/BankingClientCallback.kt
index e23c4c0e..e18fe881 100644
--- a/BankingClient/src/commonMain/kotlin/net/codinux/banking/client/BankingClientCallback.kt
+++ b/BankingClient/src/commonMain/kotlin/net/codinux/banking/client/BankingClientCallback.kt
@@ -1,5 +1,6 @@
 package net.codinux.banking.client
 
+import net.codinux.banking.client.model.MessageLogEntry
 import net.codinux.banking.client.model.tan.EnterTanResult
 import net.codinux.banking.client.model.tan.TanChallenge
 
@@ -7,4 +8,11 @@ interface BankingClientCallback {
 
     fun enterTan(tanChallenge: TanChallenge, callback: (EnterTanResult) -> Unit)
 
+    /**
+     * An optional method, for sure not available for all client implementations (currently only for FinTs4kBankingClient).
+     *
+     * Gets fired when a FinTS message get sent to bank server, a FinTS message is received from bank server or an error occurred.
+     */
+    fun messageLogAdded(messageLogEntry: MessageLogEntry)
+
 }
\ No newline at end of file
diff --git a/BankingClient/src/commonMain/kotlin/net/codinux/banking/client/SimpleBankingClientCallback.kt b/BankingClient/src/commonMain/kotlin/net/codinux/banking/client/SimpleBankingClientCallback.kt
index e1fd00f4..b63955c8 100644
--- a/BankingClient/src/commonMain/kotlin/net/codinux/banking/client/SimpleBankingClientCallback.kt
+++ b/BankingClient/src/commonMain/kotlin/net/codinux/banking/client/SimpleBankingClientCallback.kt
@@ -1,9 +1,11 @@
 package net.codinux.banking.client
 
+import net.codinux.banking.client.model.MessageLogEntry
 import net.codinux.banking.client.model.tan.EnterTanResult
 import net.codinux.banking.client.model.tan.TanChallenge
 
 open class SimpleBankingClientCallback(
+    protected val messageLogAdded: ((MessageLogEntry) -> Unit)? = null,
     protected val enterTan: ((tanChallenge: TanChallenge, callback: (EnterTanResult) -> Unit) -> Unit)? = null
 ) : BankingClientCallback {
 
@@ -15,4 +17,8 @@ open class SimpleBankingClientCallback(
         }
     }
 
+    override fun messageLogAdded(messageLogEntry: MessageLogEntry) {
+        messageLogAdded?.invoke(messageLogEntry)
+    }
+
 }
\ No newline at end of file
diff --git a/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/BridgeFintTsToBankingClientCallback.kt b/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/BridgeFintTsToBankingClientCallback.kt
index 397da3f9..af888fb3 100644
--- a/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/BridgeFintTsToBankingClientCallback.kt
+++ b/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/BridgeFintTsToBankingClientCallback.kt
@@ -1,6 +1,7 @@
 package net.codinux.banking.client.fints4k
 
 import net.codinux.banking.client.BankingClientCallback
+import net.codinux.banking.client.model.MessageLogEntryType
 import net.codinux.banking.fints.callback.FinTsClientCallback
 import net.codinux.banking.fints.messages.datenelemente.implementierte.tan.TanGeneratorTanMedium
 import net.codinux.banking.fints.model.BankData
@@ -32,6 +33,12 @@ open class BridgeFintTsToBankingClientCallback(
     }
 
     override fun messageLogAdded(messageLogEntry: MessageLogEntry) {
+        val mapped = net.codinux.banking.client.model.MessageLogEntry(
+            MessageLogEntryType.valueOf(messageLogEntry.type.name),
+            messageLogEntry.message, messageLogEntry.messageTrace,
+            messageLogEntry.error, messageLogEntry.time
+        )
 
+        bankingClientCallback.messageLogAdded(mapped)
     }
 }
\ No newline at end of file
diff --git a/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kBankingClient.kt b/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kBankingClient.kt
index 10bb9328..a6a29432 100644
--- a/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kBankingClient.kt
+++ b/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kBankingClient.kt
@@ -7,14 +7,19 @@ import net.codinux.banking.client.model.request.GetAccountDataRequest
 import net.codinux.banking.client.model.response.GetAccountDataResponse
 import net.codinux.banking.client.model.response.Response
 import net.codinux.banking.fints.FinTsClient
+import net.codinux.banking.fints.config.FinTsClientConfiguration
 
 open class FinTs4kBankingClient(
+    config: FinTsClientConfiguration = FinTsClientConfiguration(),
     callback: BankingClientCallback
 ) : BankingClient {
 
+    constructor(callback: BankingClientCallback) : this(FinTsClientConfiguration(), callback)
+
+
     private val mapper = FinTs4kMapper()
 
-    private val client = FinTsClient(BridgeFintTsToBankingClientCallback(callback, mapper))
+    private val client = FinTsClient(config, BridgeFintTsToBankingClientCallback(callback, mapper))
 
 
     override suspend fun getAccountDataAsync(request: GetAccountDataRequest): Response<GetAccountDataResponse> {
diff --git a/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kBankingClientForCustomer.kt b/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kBankingClientForCustomer.kt
index 0680e75d..e9256d28 100644
--- a/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kBankingClientForCustomer.kt
+++ b/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kBankingClientForCustomer.kt
@@ -3,11 +3,15 @@ package net.codinux.banking.client.fints4k
 import net.codinux.banking.client.BankingClientCallback
 import net.codinux.banking.client.BankingClientForCustomerBase
 import net.codinux.banking.client.model.AccountCredentials
+import net.codinux.banking.fints.config.FinTsClientConfiguration
 
-open class FinTs4kBankingClientForCustomer(credentials: AccountCredentials, callback: BankingClientCallback)
-    : BankingClientForCustomerBase(credentials, FinTs4kBankingClient(callback)) {
+open class FinTs4kBankingClientForCustomer(credentials: AccountCredentials, config: FinTsClientConfiguration = FinTsClientConfiguration(), callback: BankingClientCallback)
+    : BankingClientForCustomerBase(credentials, FinTs4kBankingClient(config, callback)) {
 
     constructor(bankCode: String, loginName: String, password: String, callback: BankingClientCallback)
-            : this(AccountCredentials(bankCode, loginName, password), callback)
+        : this(bankCode, loginName, password, FinTsClientConfiguration(), callback)
+
+    constructor(bankCode: String, loginName: String, password: String, config: FinTsClientConfiguration = FinTsClientConfiguration(), callback: BankingClientCallback)
+            : this(AccountCredentials(bankCode, loginName, password), config, callback)
 
 }
\ No newline at end of file