Interoperability Issues

Technical description of the reason for some failures are listed here

budgetvoip.com

Through trial and error someone was able to get calls working by setting sRTP encryption to disabled. The default is set to optional, which resulted in:

SIP/2.0 488 Not acceptable here

1&1

This provider requires a public IP address in the Contact header. This is plain wrong as explained here.

placetel.de

This provider requires a public IP address in the Contact header. This is plain wrong as explained here.

Mitel PBX

There are reports that Blink does work with Mitel equipment. We had not find such hardware to test with but rumor has it the reason is the fact that Mitel sends INVITE with no SDP considering everything is a audio call. Blink as a multimedia client needs to know what type of media is proposed in order to start a session. We did a synthetic test and hack to handle this in Blink, but nobody could confirm it works.