A bit of Germany, a bit of Taiwan. One of the problems of these feature monsters is not only the number of software bugs, lack of expertise in Software Security and Software Usability, but the general lack of Computer Scientists. Not uncommonly, such devices are made by people who moved over from hardware and struggle to cope with current software now. Just an example: I found no way to use the device not as a router but as DHCP/IP client without NAT.
12.39.2.03.01 downgrade to that version to re-enable sRTP
12.39.2.05.00
retested in May 2020 with 12.39.2.06.03
| Password: | printed at the bottom of the device |
| HTTPS: | enabled on default |
| Update: | Options → Expert view → System → Firmware Update |
| Trust Anchors: | just Telekom Deutschland is built-in |
| SIP-URI Host: | Telephony → VoIP Provider → New → Account domain |
| SIP-URI User: | Telephony → Call Number → VoIP Numbers → New → Account name |
| SIP-over-TLS: | Telephony → VoIP Provider → Edit → Protocol: TLS requires firmware 12.39.2.03.01; after a firmware update, the device still uses TLS but cannot be changed anymore; new accounts offer UDP or TCP only |
| SDES-sRTP: | Telephony → VoIP Provider → Edit → Call encryption VoSIP which is RTP/SAVP; requires TLS to be set |
| Dialing: | on default, adds 00 before each dialed number can be changed to ‘+’: Telephony → General → International call prefix. However, since firmware 12.39.2.04.00, the device requires an area code, why ever. |
| SHA-2 Digest: | does not pick MD5, continues without header Authorization, therefore is not able to register; therefore incompatible with Linphone |
| Server TLS: | when using the SIP B2BUA, only UDP but not TLS is offered |
| Signaling DiffServ: | not CS5 but CS6; this is considered a bug and not just a bad default because no way was found to change this default (useful for the ITA mode, for example) |
| Bugs: | SIP-over-TLS without authentication (for generic accounts) |
| Responsible Disclosure: | try E-mail, alternatively go via Deutsche Telekom CERT |
| Firmware Update: | missing Newsletter Mitigation: Router-FAQ |
12 V 3 A, Coaxial: 5.5 mm × 2.1 mm