How to make virtual prefix to call another extension on 3rd party PBX

We collected the below info from customer in oder to check his needed solution :

1- Version of the U1960 : V200R003C30 

2- Version of the IP phons under U1960 : IP phones 7950 V200R003C30 

3- 3rd Party PBX is having soft phones registered under it 

4- U1960 and 3rd party PBX is connected using SIP trunk 

5- We asked him about the office route for the SIP trunk and he said it is the same as the one we used for prefix 9 , so we asked him for snapshot and we found that prefix 9 is using office route 1 as per below snapshot 

6- We checked the call connectivity between the U1960 and other 3rd party PBX and they are working fine

Customer requiremnet :

He need when he dial from Huawei IP phone under U1960 1401 the call should go to the SIP trunk to 3rd party PBX and extension 201 will ring 

- There are no extension 1401 under the U1960

- Customer need 1401 to be virtual as there is not IP phone under U1960 with this extension numebr 

Solution provided :

1- We created change number index with index 55 to change the 1140 to be 201 as per below snapshot 

2- We created prefix 1140 to match the customer needed so that he need the users to dial 1140 from the U1960 then to make called number change with the above changes to change the called number from 1140 to be 201 as per below snapshot 

Solution results :

1- We make customer dial from any Huawei IP phone 1140 

2- The call went throught the SIP trunk with office route 1 

3- Then the called number changed from 1140 to be 201 and the soft phone under the 3rd party PBX with 201 number rings 

4- Issue has been solved