A TCP check from Bulgaria attempts a handshake to your host on a specified port from our Sofia node at Telehouse and reports connection time. From Sofia, TCP connect times to Bucharest-hosted servers are typically 15–18 ms, to Frankfurt 40–48 ms, and to Istanbul 28–35 ms. TCP checks are more informative than ping for verifying real application port reachability because they go through firewall rules and routing policy the same way actual application traffic does.

Bulgarian ISPs and datacenter providers do not commonly filter outbound ports on commercial connections. The Telehouse Sofia facility operates with standard datacenter-grade port policies. If a TCP check from Bulgaria fails while Western European nodes succeed, the most common explanations are: the destination is blocking the Aluy AS211507 source range, there is a geo-block applied to Bulgarian IP space, or the return path is failing due to asymmetric routing. Check your firewall logs for the probe's source IP to rule out an IP reputation block.

Bulgaria is a useful test reference for services operating in the EU's southeastern markets. Some financial and compliance-driven services apply stricter rules to Eastern EU countries than to Western EU — a TCP failure from Sofia while Germany succeeds might reflect an intentional restriction rather than a network problem. Cross-checking against our Romanian and Croatian probes helps isolate whether the behavior is Bulgaria-specific or affects southeastern EU broadly.

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.