SIP Trunk – ANTEL URUGUAY – Part 3

For our readers in Uruguay, we explain the implementation of ANTEL's SIP Trunk, hoping it will be useful when contracting the service. ANTEL has migrated its telephony core to IP, but until now has maintained last-mile connectivity through traditional means, analog and digital lines (PRI, R2, BRI) using Media Gateways that perform media conversion. This new service will allow communication to be completely end-to-end IP, from the signaling servers to the customer's site without the need for intermediate equipment in the call path to convert different media (IP-analog, IP-TDM, or IP-GSM/3G). Implementation in ANTEL ANTEL's SIP trunk service can be provided through any access medium available at the client's site, whether dedicated fiber, FTTH, or copper. Because the maximum number of simultaneous calls the Trunk can support depends on the access medium, this is an important factor to consider when contracting the service. Clients will be able to originate and receive calls from or to any other ANTEL or third-party fixed or mobile phone, domestic and international. When contracting this service, the client can choose from various plans for the number of simultaneous calls and telephone numbers. It will be possible to migrate numbers currently in use by the client to the contracted Trunk. For the migration, in a first stage, the client must install a Trunk with new numbers, and in a second stage, the numbers they need to migrate will be added. ANTEL's MPLS network is used as transport to reach the NGN network. Because calls are not transported over the Internet High security and quality of service can be guaranteed. Throughout ANTEL's network, calls are prioritized over other data. However, if the client interconnects the service with other networks, it is recommended that they install an edge device (Firewall, E-SBC) between the PBX and the service connection. Good news, 3CX is offering its SBC for free!   SBC patents are expensive. 3CX offers it free of charge to all 3CX Phone System users. 3CX SBC is a tunnel included in 3CX Phone System that makes it much easier to connect remote offices via bridges and remote extensions. https://www.3cx.com/docs/3cx-tunnel-session-border-controller/#h.pnclxubq0wh9 SIP Trunk Configuration The service will be provided to the client through an RJ45 port. The Client must configure the following data on their IP PBX, which ANTEL will provide: ANTEL SIP Server IP: IP to which the client should send SIP packets. Client IP: IP from which the client should send SIP messages. It must be configured in PBX or Edge Equipment. Default Gateway: IP that must be configured as Default Gateway to route packets to the Antel network. Mask: Mask that the client must configure for the subnet where the “Client IP” is included Telephone numbers: Numbers that the Client can use in the Trunk. It is important that the Client's outgoing calls have the CID configured with these numbers. Otherwise, the call will be rejected or will go out with the number included by default in the service. Simultaneous calls: Number of simultaneous channels the client will be able to use. The client must also configure the following parameters: Source and destination SIP port: 5060 Supported codecs: G.711, T.38 Supported DTMF protocols: INBAND, RFC 2833 Session Expire (RFC4028): 600 NOTE: ANTEL trunk does not use SIP registration (no username and password are used). Antel sends the “OPTION” message as a heartbeat and the client equipment must automatically respond to this heartbeat with the message “200 OK” as shown in the following Wireshark capture example: SIP Trunk Security Aspects The client's IP PBX connects to the Public Telephony Network through Antel's Private Network, which ensures the security and quality of the service. It is important for the client to carefully manage their internal networks to avoid security issues with their IP PBX, just as they would with a server. Some recommended security measures include: using VLANs to separate the client's internal networks; correctly configuring the Firewall or E-SBC to prevent client Internet traffic from reaching the IP PBX, gateways, and IP phones; and limiting TCP and UDP ports that can access the IP PBX. Possible topologies: Because SIP packets have an IP in the payload in addition to the network IP, this can cause difficulties if you want to do NAT. If the router is not able to interpret SIP, it will only change the network IP and will not be able to change the SIP IP within the payload. Topology 1 – E-SBC: If the client has an E-SBC, it will handle SIP communication with ANTEL's server. The PBX will have a private IP addressing defined by the client in both the network layer and the payload (SIP). When the packet arrives from the PBX to the E-SBC, the IPs are translated to the Trunk IPs provided by ANTEL. As the E-SBC interprets SIP packets, it is capable of translating the payload IP. The E-SBC will function as a telephony firewall, providing security, controlling, and logging all SIP communications. This topology is recommended when interconnection between the Trunk network and other networks is required. Topology 2 Firewall: In this topology, the client connects a firewall between the PBX and the ANTEL network, but SIP communication will be between the PBX and the ANTEL server. The PBX will have a private IP addressing defined by the client at the network layer, but in the payload (SIP), the PBX must already incorporate the address provided by ANTEL because the firewall cannot translate this IP (most firewalls are not designed for telephony). In a standard firewall, a common error occurs when the packet arrives from the PBX to the firewall, the network IP is translated to the IP provided by ANTEL, but the payload IP is not updated. The firewall provides security, but it must also be configured correctly so that it does not block the data packet ports for calls. Topology 3 Without Equipment: In this topology, the client connects the PBX directly via UTP cable to the ANTEL equipment. The configuration is the simplest. The trunk IPs provided by ANTEL are configured on the PBX, both at the network layer and in the payload (SIP). It is recommended to use this “no equipment” topology when the client does not need to interconnect the Trunk network with other networks. Note: It is not recommended to connect the Trunk to a switch shared with other devices, due to security aspects and limitations in the ANTEL Modem's MAC table. In this case, it is recommended to use VLANs or one of the previous topologies. SIP Trunk Functional Testing To check the operation of the SIP Trunk, it is recommended to perform the following tests: Connectivity Tests: Ping the Default Gateway IP Ping 190.64.60.4 and 190.64.60.20 Note: The SIP server IP does not respond to ping requests due to security reasons, so IPs 190.64.60.4 and 190.64.60.20 are used to test connectivity. Trunk Tests: – Outgoing and incoming calls: local, internal, cellular (ANTEL and other companies), international – Make and receive multiple simultaneous calls – Make a call lasting over 10 minutes – Fax operation – G.711 codec – DTMF SIP Header Format: As an example, it is shown what the SIP protocol's INVITE should look like for a particular outgoing call: Destination number to call: yxxxxxxx ANTEL Server IP: 190.64.60.10 Client IP: wwww Customer phone number: zvvvvvvv INVITE yes: yxxxxxxx @190.64.60.10:5060 SIP/2.0 Via: SIP/2.0/UDP wwww<sip: zvvvvvvv @ wwwwto: <sip: yxxxxxxx @190.64.60.10:5060> From: « zvvvvvvv « zvvvvvvv @ wwww:5060>;tag=620f0b37 Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REGISTER, SUBSCRIBE, NOTIFY, REFER, INFO, MESSAGE Remote-Party-ID: « zvvvvvvv « zvvvvvvv @ wwww:5060>;party=calling   SIP Trunk Maintenance and Complaints To claim the service the client can call 0800-2599 where they will have 24/7 technical support. Customers must file complaints using the Troncal service number. It is important that customers write down this number at the time of service installation so they can file service complaints quickly. Note: Do not confuse the Troncal service number with your phone numbers. The service number consists of the letter P followed by 5 digits. Example: P12345 If the service must remain operational during a power outage, we recommend that the customer add a backup power supply to their IP PBX and to the modem connected to the ANTEL network. _____________________________________ Looking for advice to hire a SIP trunk for your company? Talk to an expert. At SimpleTECH We can help you. We have the specialized knowledge necessary for the change process to run completely smoothly and without problems. Consult us. We are the only Spanish-speaking Platinum and Support Partner of 3CX in Latin America.   By: The team of SimpleTECH© Montevideo, Uruguay Sources: Antel Uruguay www.antel.com.uy