GPRS AT Command CGDCONT - Do I really need an APN? -

GPRS AT Command CGDCONT - Do I really need an APN? -

i developing embedded firmware communicate multi-tech's mtsmc-h5 gprs modem. unclear utilize of at+cgdcont command. in h5 modem's reference guide, states command format is

>at+cgdcont=[<cid>[,<pdp_type>[,<apn>[,<pdp_addr>[,<d_comp> >[,<h_comp>[,<pd1>[,…[,pdn]]]]]]]]] >... ><apn> access point name. string parameter logical name used select >ggsn or external packet info network. if value empty (“”) or omitted, >3gpp ts 27.007 @ commands subscription value requested. >...

what effect if leave apn field blank? seems can connect cell network while leaving apn field blank. tried several sim cards , seem work without specifying apn field. however, i'd know sure appropriate. because have limited ui capability (no real keypad on device modem attached to), highly desirable if end user not have come in apn information.

the apn stored on sims used. in cases, ok found out. there few border cases might run problems, such apn changing (rare), or arrangements between individual operators, or between operators , customers.

even these cases can mitigated operators automatically right wrong apn (apn redirection).

note not behaviour mandatory under 3gpp standards, may vary operator operator.

command at-command gprs apn