voip problems

[Erez D]

Hi.
I am abroad and using voip to call my family and other israeli phones.
I use my cell phone as a sip client and connect via wifi to my asterisk box which connects to an ht488 (fxo) which is connected to a bezeq line.
Until a few days ago everything worked great. However, in the last days, whenever i try to call phones i get an "address busy" error.
Note that i am able to connect  to the voicemail on the asterisk box.
I tried to restart both my asterisk and my ata, but the problem remains.

Any idea ?

Thanks,
Erez.