SIP protocol..

SIP is a application layer protocol, used in VOIP communication.

SIP uses standard port as 5060.

SIP uses UDP as a transport layer , but when packet size crosses 1000 bytes ( usually 800 bytes ) . in IMS network SIP packet may crosses 1000 bytes, because of too many headers.

Software Testing

Software testing is a process, which helps to find out the bugs in the software and get it fix from the developers, before it is delivering to the customer.

most of the time software testing is using the application like an end user or customer.

 

there are different ways to test a particular software   :

  1. Performance Testing
  2. Load Testing
  3. Regression Testing
  4. Sanity Testing
  5. Smoke Testing
  6. Cursory Testing

Um Interface

A mobile device and BTS link ( Air interface ) is called as Um Interface.

GSM uses 900 and 1800 MHZ frequency .

in GSM 900 uplink range is 890 to 915 MHZ, and downlink  range is 935 to 960 MHZ.

here u can observe less frequency is assigned for uplink , i.e from UE to BTS. this is because UE require more power to generate highest frequency. UEs are equipped with battery. so to enhance the battery usage less frequency rage is assigned for uplink.