Jumper setting 

Jumpering means to temporarily complete a circuit or to bypass a break in a circuit by making a connection from one point to another.

A good conductor wire is used to make a jumper which by-passes the components and passes on a signal or supply line for further uses.

When wire is used as a jumper, it must have some special specifications as required. These jumper wires can mainly be of two types i.e. insulated and non-insulated. In the mobile phone insulated wires are used for jumpers. The length of a jumper depends on the two points connected in between.

Why is jumpering needed ?

While repairing mobile phones, we find that certain faulty components are very difficult to get from the market. To repair such mobile phones the only immediate option is the use of jumpers. By use of jumpers we will bypass the faulty components specifically. 

How to Jumper

Disassemble mobile phone and place it on a PCB holder.

Using a multimeter, check track and find the fault or the missing track that need jumper.

Apply liquid soldering flux to the points where you need to solder jumper wire.

Cut jumper wire to desired length and remove its lamination using blade cutter.

Hold one end of the jumper wire and solder it to one point of the faulty circuit track. Use a good quality tweezers to hold the wire and good quality of soldering iron and solder wire to solder.

Now hold the other end of the jumper wire and solder to the other point of the track

Using a multimeter check the jumper.

Cell Phone Jumper Setting

jumper setting is typically best when you need to connect two different points on a cell phone there could be internal disturbances in the circuit of the handset which are connecting these two points and

because of the internal disturbance or a breakage in the circuit, the father or data may not be traveling

from one point to the other easily and in those cases, we use jumper setting to try and connect those two points directly thereby ensuring the correct transmission of power, data, and piles voltage from one end to the other end but in order to determine whether you need to do jumper setting.

for example, if you're checking a battery connector you may need to first verify whether the battery connector is working properly or not before you decide to make any changes or test any connections on the cell phones

Thank you 

@kyaps Barnabas