UMTS terminating call issue

[Jerry]

Dear all,

We have some customers complain that they got many missed calls (call logs) but they havent seen any imcoming calls. The caller said that they hear no ringback tone then got ann 'subs is unavailable' after 10-20s.

The called number is most of time in 3G, when we check the signal strength is quite ok (RCSP ~75dBm).

Sub used iPhone 5.

My quesrion is why they got missed call (in call logs) but called number got 'unavailable'? Is it handset problem? Anyone using iPhone 5 get same?

Hopeful got your advise.

[s.saadhassan]

Do you have LTE in your network? If so, what is the solution for voice?

If you are using LTE with CSFB, then it is possible the user gets stuck on LTE (wrong CSFB config). This gives calling party 'Unavailable' message, and called party gets a missed call notification later..

[Muhammad Imran Rafique]

hi Jerry,

its purely a problem where CORE is not able to page subscriber properly, it happens in live NW. Please forward to CORE and do field test with coordination of all related departments. Nothing form RAN side.

[dtvt2]

Hi friend
- Maybe there is external interference in uplink. pls check RTWP

[erastus]

Try using the same SIM card in another phone model and if the problem persists, then there could be a problem with the SIM card profile in the HLR.

[oswe]

we have the same in an NSN network, but..... the RNC NPGEP boards are fullly loaded giving many .rnc failures in rab procedures. have you checked that ?

[tharinduwije]

You need check this kind of issues with a end to end traces covering RNC & MSC communication.Its hard to say which fails where without Tracing.