diff --git a/docs/tasks.md b/docs/tasks.md
index 735221d..dacfa3a 100644
--- a/docs/tasks.md
+++ b/docs/tasks.md
@@ -127,6 +127,7 @@ container's `/etc/hosts` file; the keys are the hostnames, and the values
 are the IP addresses;
 * `sysctls`: a dictionary of kernel sysctl parameters to add to the container;
 keys are the names of the kernel parameters and values are their values;
+* `working_dir`: can be used to overwrite the default working_dir of the image;
 
 You can find the specific settings for each task type in their corresponding
 file in the  [tasks](tasks) directory.
diff --git a/docs/tasks/sipp.md b/docs/tasks/sipp.md
index be78600..ea1915e 100644
--- a/docs/tasks/sipp.md
+++ b/docs/tasks/sipp.md
@@ -42,7 +42,9 @@ usually `sipp` (see `sipp -s` parameter for more information).
 added to the `keys` dictionary as well, but the default value is the name of 
 the SIPssert scenario
 
-## Example
+## Examples
+
+### SIPp scenario with config_file
 
 Execute a sipp scenario defined in the `cancel.xml` file, with a domain key:
 
@@ -53,3 +55,30 @@ Execute a sipp scenario defined in the `cancel.xml` file, with a domain key:
    keys:
      domain: opensips.org
 ```
+
+### SIPp with TLS transport
+
+When using TLS transport, SIPp will expect to have two files in the current directory: a certificate (cacert.pem) and a key (cakey.pem). If one is protected with a password, SIPp will ask for it.
+
+Create a docker volume and place the certificate files in it.
+Mount volume with certificates to the container and setup working_dir to that folder.
+Specify in the args to use the TLS transport with options "-t l1".
+
+```
+tasks:
+...
+  - name: tls client
+    type sipp
+    config_file: invite.xml
+    working_dir: /certs
+    args: "-t l1"
+    volumes:
+      - sipp-certs
+...
+
+volumes:
+  sipp-certs:
+    bind: /certs
+    mode: ro
+
+```
\ No newline at end of file
diff --git a/sipssert/task.py b/sipssert/task.py
index 1ec8cee..dc5b7a7 100644
--- a/sipssert/task.py
+++ b/sipssert/task.py
@@ -59,6 +59,7 @@ def __init__(self, test_dir, configuration):
         self.checklogs = self.get_checklogs()
         self.extra_hosts = self.config.get("extra_hosts", {})
         self.sysctls = self.config.get("sysctls", {})
+        self.working_dir = self.config.get("working_dir")
         self.deps = dependencies.parse_dependencies(self.config.get("require"))
         # keep this for backwards compatibility
         self.delay_start = self.config.get("delay_start", 0)
@@ -171,6 +172,7 @@ def create(self, controller, prefix=None):
                            'stop_signal': self.stop_signal,
                            'network_mode': self.host_network,
                            'extra_hosts': self.extra_hosts,
+                           'working_dir': self.working_dir,
                            'sysctls': self.sysctls
                           }