[asterisk-users] Choosing codecs

[Luca Bertoncello]

Hi list!

I noticed that when the phone of my wife calls the gsm codec will be used,
but if someone calls the phone, alaw will be used:

00493511111111 calls 00493512222222:
OpenWrt*CLI> sip show channels
Peer             User/ANR         Call ID          Format           Hold     Last Message    Expiry     Peer      
192.168.200.11   00493512222222   5305ad0e07977dd  0x4 (ulaw)       No       Init: INVITE               0049351222
192.168.200.10   00493511111111   1481837b-c0a801  0x4 (ulaw)       No       Rx: INVITE                 0049351111

00493512222222 calls 00493511111111:
OpenWrt*CLI> sip show channels
Peer             User/ANR         Call ID          Format           Hold     Last Message    Expiry     Peer      
192.168.200.10   00493511111111   5e21076a01b9483  0x8 (alaw)       No       Tx: ACK                    0049351111
192.168.200.11   00493512222222   MCBsoNI2Cj266BB  0x2 (gsm)        No       Rx: ACK                    0049351222

Could someone explain me why?
Second question: I think, ulaw/alaw are better then gsm, isn't it?
If so, how can I change it?

Thanks
Luca Bertoncello
(lucabert at lucabert.de)