The degree of versatility that dual SIM technology provides is simply unmatched by single SIM devices, as can be seen when contrasting dual SIM slots with conventional single SIM options. Havingvisa slots for germany only one number and one plan on a single SIM phone can be restrictive in a number of situations. For example, people who travel a lot might have to change their SIM cards all the time or pay expensive roaming costs when using a single line overseas. Dual SIM functionality, on the other hand, eliminates the inconvenience of physically switching cards & enables smooth network switching.