From field user part incomplete on some outbound calls

[oliv]

Hello,

I've got a newly installed T53 on a remote site, registered to an Asterisk instance.

I've got a pcap file in which for the first outbound call, in primary outbound INVITE, From field is set like this:
From: <sip:192.168.1.1>;tag=123456

In the second call, the From field is set like this:
From: "MyName" <sip:username@1.2.3.4:5060>;tag=123456

1.2.3.4 is Asterisk's IP address.
192.168.1.1 is T53's IP address.

What could be the source of this difference ?

Best regards