diff --git a/pyVoIP/SIP/client.py b/pyVoIP/SIP/client.py
index 7d17aed..b8cdd7d 100644
--- a/pyVoIP/SIP/client.py
+++ b/pyVoIP/SIP/client.py
@@ -417,6 +417,8 @@ def gen_digest(
         user = request.headers["From"]["user"]
         credentials = self.credentials_manager.get(server, realm, user)
         username = credentials["username"]
+        if request.authentication["header"].lower() == "proxy-authenticate":
+            username = credentials["user"]
         password = credentials["password"]
         nonce = request.authentication["nonce"]
         method = request.headers["CSeq"]["method"]