A method of seamlessly connecting over-the-top, OTT, networks and Traditional Telecommunication Networks, TTN, comprising: receiving by a TTN Telecommunications Service Provider, TSP, from a calling party a dialed number of a called party; communicating by said TSP the dialed number in parallel to an OTT service provider and to a TTN service provider; checking in parallel: a. by said OTT service provider whether it can terminate said call; said checking comprising: checking whether the dialed number is associated with a registered member of said OTT service; checking whether the called party is currently online; checking the called party's routing preferences; and checking whether the connectivity between the OTT service provider and the called party is adequate, by performing a communication test and checking which type of network is currently being used by the called party; and communicating said checking results to the TSP; and b. by said TTN service provider whether it can terminate said call; and communicating said checking results to the TSP; and terminating said call by one of said OTT and TTN service providers, wherein the communication test comprises at least one of: sending a small number of packets, waiting for the called party's terminal to reply, testing the arrival times of the replies and estimating connectivity; and checking the last time the called party's terminal was called or interacted with and using quality parameters measured on this last interaction. receiving by a TTN Telecommunications Service Provider, TSP, from a calling party a dialed number of a called party; communicating by said TSP the dialed number in parallel to an OTT service provider and to a TTN service provider; checking in parallel: a. by said OTT service provider whether it can terminate said call; said checking comprising: checking whether the dialed number is associated with a registered member of said OTT service; checking whether the called party is currently online; checking the called party's routing preferences; and checking whether the connectivity between the OTT service provider and the called party is adequate, by performing a communication test and checking which type of network is currently being used by the called party; and communicating said checking results to the TSP; and b. by said TTN service provider whether it can terminate said call; and communicating said checking results to the TSP; and a. by said OTT service provider whether it can terminate said call; said checking comprising: checking whether the dialed number is associated with a registered member of said OTT service; checking whether the called party is currently online; checking the called party's routing preferences; and checking whether the connectivity between the OTT service provider and the called party is adequate, by performing a communication test and checking which type of network is currently being used by the called party; and communicating said checking results to the TSP; and checking whether the dialed number is associated with a registered member of said OTT service; checking whether the called party is currently online; checking the called party's routing preferences; and checking whether the connectivity between the OTT service provider and the called party is adequate, by performing a communication test and checking which type of network is currently being used by the called party; and communicating said checking results to the TSP; and b. by said TTN service provider whether it can terminate said call; and communicating said checking results to the TSP; and terminating said call by one of said OTT and TTN service providers, wherein the communication test comprises at least one of: sending a small number of packets, waiting for the called party's terminal to reply, testing the arrival times of the replies and estimating connectivity; and checking the last time the called party's terminal was called or interacted with and using quality parameters measured on this last interaction. sending a small number of packets, waiting for the called party's terminal to reply, testing the arrival times of the replies and estimating connectivity; and checking the last time the called party's terminal was called or interacted with and using quality parameters measured on this last interaction.