Update intiate_mobile_transaction.md

docs/intiate_mobile_transaction.md

@@ -21,4 +21,24 @@ method|String|Limited to only ecocash at the time of writing
 
 > **NOTE:** The integration ID being used for a mobile money transaction cannot be in test mode. The integration ID must also have an Ecocash payment method selected for use in the Paynow setup area. 
 
-Failure to conform to these requirements will result in an error being returned during the initiate mobile money transaction request with an error description relating to this fact
+Failure to conform to these requirements will result in an error being returned during the initiate mobile money transaction request with an error description relating to this fact
+
+
+### Express Checkout Test Mode
+
+To use mobile money Express Checkout in test mode, there are four pre-configured mobile numbers that can be used to simulate various results: 
+
+*N.B. The authemail field supplied during test mode should match one of the login email addresses for the merchant account being tested.*
+
+> Success – 0771111111
+
+Paynow will send a SUCCESS status update message 5 seconds after the transaction is initiated.
+
+> Delayed Success – 0772222222
+Paynow will send a SUCCESS status update message 30 seconds after the transaction is initiated. This simulates the user taking a longer than normal amount of time to authorize the transaction from their handset
+
+> User Cancelled – 0773333333
+Paynow will send a FAILED status update message 30 seconds after the transaction is initiated. This simulates the user cancelling the mobile money transaction.
+
+> Insufficient Balance – 0774444444
+Paynow will immediately fail the transaction during initiation and return an “Insufficient balance” error message.