UDP checks from Bulgaria send a packet from our Sofia node to your specified port and wait for a response. Telehouse Sofia has standard datacenter connectivity with no unusual UDP restrictions outbound. A no-response result reflects the destination firewall or application policy, not a Bulgarian network restriction. This check is particularly useful for testing VPN endpoints, game servers, SIP gateways, and DNS resolvers from a Southeastern European perspective.

Sofia's position makes it a relevant UDP test point for services targeting Eastern Mediterranean and Balkan users. Latency from Sofia to Istanbul is around 30 ms and to Athens around 32 ms. For game server or VoIP operators assessing whether to add a Balkan PoP, UDP test results from our Sofia probe combined with results from our Romanian and Serbian probes give a multi-country view of regional reachability.

A UDP failure from Bulgaria while TCP succeeds on the same host means UDP is being filtered — either at the host firewall, a cloud security group, or an intermediate stateful firewall. A failure on both protocols from Bulgaria while other EU nodes succeed points to Bulgarian IP space being blocked. To narrow it down, compare against our Romanian node: both are on AS211507 (Aluy). If both fail, the block is likely applied to the entire AS range rather than to Bulgarian IPs specifically.

Sofia is the center of Bulgarian internet infrastructure. BIX (Bulgarian Internet Exchange) is the country's primary neutral IX, connecting Bulgarian ISPs, hosting providers, and content networks in Sofia. BIX carries significant regional traffic and is the main peering point for keeping domestic Bulgarian traffic from transiting out of the country. Equinix also operates a colocation facility in Sofia, which added a second neutral peering point and brought international carrier presence directly into the Bulgarian market.

Bulgaria has been an EU member since 2007, and EU investment has helped modernize parts of its broadband infrastructure. Fiber penetration in Sofia and other major cities is solid, though rural coverage remains uneven. The major fixed ISPs are Vivacom (AS8866), A1 Bulgaria (AS6802), and Bulsatcom (AS34224). Vivacom operates the largest national backbone and provides significant transit capacity. Telus International Bulgaria (formerly TTEC) and other technology companies have large operations in Sofia, creating steady demand for quality datacenter connectivity.

Telehouse Sofia is the primary carrier-neutral datacenter in the country and the most connected facility in Bulgaria. It hosts BIX and a large number of ISP and hosting provider PoPs. Sofia's geographic position gives it natural routing relevance for traffic between Western Europe and Turkey, Greece, and the Middle East — paths that transit the Balkans must pass close to Sofia regardless of direction. Several Tier-1 and Tier-2 transit providers maintain Sofia PoPs specifically for this transit role.

Latency from Sofia to other regional cities: Bucharest is around 15 ms, Istanbul around 30 ms, Athens around 30–35 ms, Belgrade around 20 ms, and Frankfurt around 40–45 ms. These figures reflect the direct transit paths available from Sofia. Bulgaria is one of the lower-cost EU hosting jurisdictions, which has made it attractive for operators wanting EU-legal status for their infrastructure at lower colocation prices than Frankfurt or Amsterdam.

Our probe node is in Sofia, on AS211507 via Julian Achter (Aluy), colocated at Telehouse Sofia. This puts the probe in the best-connected facility in the country with access to BIX peering and multiple upstream transit providers. Tests from this node reflect conditions typical of Sofia-hosted services and are broadly representative of Bulgarian network performance. The Telehouse Sofia location means latency from the probe to BIX-connected networks is minimal.