At first it didnt happen but after some time this problem appeared and wont work anymore until reinstall, but after some time it happens again.

What steps will reproduce the problem?

becomes necessary to close completely Sipdroid using the exit option menu and then running it again.

The problem occurs when making an outgoing call using the native codec gsm, speedx, the call connects but the application crash.

What is the expected output? Instead What do you see?

The logcat says:

org.sipdroid.sipua dalvikvm JNI ERROR: env -> self != theread-self (.... vs .....);

org.sipdroid.sipua libc Fatal signal 11 (SIGSEGV) at ...... code=1.....

What version of the product are you using? On what device / operating system?

Sipdroid 3.6 beta and Samgsung Galaxy S3 (GT-I9300) with android 4.3.

Which SIP server are you using? What happens With PBXes?

I'm using a sip account generated through PBXes 8did.com

Which type of network are you using?

the problem occurs in networks 3g, h+, wlan.