--- title: "SIP Backbone – ANTEL URUGUAY – Part 3" id: "241" type: "post" slug: "troncal-sip-empresarial-antel-uruguay" published_at: "2018-03-05T14:55:19+00:00" modified_at: "2025-12-08T18:58:19+00:00" url: "https://www.simpletech.uy/en/troncal-sip-empresarial-antel-uruguay/" markdown_url: "https://www.simpletech.uy/en/troncal-sip-empresarial-antel-uruguay.md" excerpt: "We’ll explain how ANTEL’s SIP Trunk is implemented, hoping this information will be useful when you sign up for the service." taxonomy_category: - "Communications" - "Innovation" taxonomy_post_tag: - "Unified Communications" - "IT" - "Telephony" - "IP Telephony" - "SIP Trunk" --- For our readers in Uruguay, we explain the implementation of ANTEL’s SIP Trunk, hoping it will be useful when signing up for 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 enable communication to be entirely 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 between different media (IP-analog, IP-TDM, or IP-GSM/3G). **Implementation at ANTEL** ANTEL’s SIP trunk service can be provided via any access medium available at the customer’s site, whether dedicated fiber, FTTH, or copper. Since the maximum number of simultaneous calls the trunk can support depends on the access medium, this is an important factor to consider when signing up for the service. Customers will be able to make and receive calls to and from any other ANTEL or third-party landline or mobile phone, both domestically and internationally. When signing up for this service, the customer can choose from various plans based on the number of simultaneous calls and phone numbers. It will be possible to migrate numbers currently in use by the customer to the contracted trunk. For the migration, in the first stage, the customer must install a Trunk with new numbers, and in the second stage, the numbers to be migrated will be added. ANTEL’s MPLS network is used as the transport medium to reach the NGN network. Because calls are not carried 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 customer 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. The 3CX SBC is a tunnel included in the 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 settings on their IP PBX, which ANTEL will provide: **ANTEL SIP Server IP:** The IP address to which the client should send SIP packets. **Client IP:** The IP address from which the client should send SIP messages. It must be configured in the PBX or edge equipment. **Default Gateway:** The IP address that must be configured as the default gateway to route packets to the ANTEL network. **Subnet Mask:** The subnet mask the client must configure for the subnet that includes the "Client IP." **Phone Numbers:** The numbers the client can use on 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 be made using 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:** The ANTEL trunk does not use SIP registration (no username or password is required). 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 Considerations** The client’s IP PBX connects to the public telephone 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 the client’s Internet traffic from reaching the IP PBX, gateways, and IP phones; and limiting the TCP and UDP ports that can access the IP PBX. **Possible topologies:** Because SIP packets contain an IP address in the payload in addition to the network IP, this can cause difficulties when performing NAT. If the router cannot 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 address defined by the client in both the network layer and the payload (SIP). When the packet arrives from the PBX at the E-SBC, the IP addresses are translated to the trunk IP addresses provided by ANTEL. Since the E-SBC interprets SIP packets, it is capable of translating the payload IP address. 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 takes place between the PBX and the ANTEL server. The PBX will have a private IP address defined by the client at the network layer, but in the payload (SIP), the PBX must already include 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 a packet arrives from the PBX at 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 used for calls. **Topology 3 Without Equipment:** In this topology, the client connects the PBX directly via UTP cable to the ANTEL equipment. This is the simplest configuration. 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 concerns 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 verify 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 for 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 carriers), 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, here is what the SIP protocol’s INVITE message should look like for a specific 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**@**wwww 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 sign up for the service, customers can call **0800-2599**, where they will receive 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** on hiring a SIP trunk for your company? Talk to an expert. At [SimpleTECH](https://www.simpletech.uy/en/index.html/) We can help you. We have the specialized knowledge needed to ensure the transition process runs completely smoothly and without issues. Contact us. We are the only Spanish-speaking Platinum and Support Partner of 3CX in Latin America. By: The team at [SimpleTECH](https://www.simpletech.uy/en/nosotros.html/) © Montevideo, Uruguay Sources: Antel Uruguay www.antel.com.uy ## We are revolutionizing the world of CX—join the transformation **We can help you with your business needs!** Leave us a message, and our experts will contact you. 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